Merge pull request #1041 from Ascrod/default-pref

Clean up try/catch blocks for preferences

34 files changed, 107 insertions, 407 deletions

diff --git a/toolkit/components/asyncshutdown/AsyncShutdown.jsm b/toolkit/components/asyncshutdown/AsyncShutdown.jsm
index 62ac36f42..9cdf9e126 100644
--- a/toolkit/components/asyncshutdown/AsyncShutdown.jsm
+++ b/toolkit/components/asyncshutdown/AsyncShutdown.jsm
@@ -79,12 +79,8 @@ const DELAY_WARNING_MS = 10 * 1000;
 // Crash the process if shutdown is really too long
 // (allowing for sleep).
 const PREF_DELAY_CRASH_MS = "toolkit.asyncshutdown.crash_timeout";
-var DELAY_CRASH_MS = 60 * 1000; // One minute
-try {
-  DELAY_CRASH_MS = Services.prefs.getIntPref(PREF_DELAY_CRASH_MS);
-} catch (ex) {
-  // Ignore errors
-}
+var DELAY_CRASH_MS = Services.prefs.getIntPref(PREF_DELAY_CRASH_MS,
+                                               60 * 1000); // One minute
 Services.prefs.addObserver(PREF_DELAY_CRASH_MS, function() {
   DELAY_CRASH_MS = Services.prefs.getIntPref(PREF_DELAY_CRASH_MS);
 }, false);
@@ -207,12 +203,7 @@ function log(msg, prefix = "", error = null) {
   }
 }
 const PREF_DEBUG_LOG = "toolkit.asyncshutdown.log";
-var DEBUG_LOG = false;
-try {
-  DEBUG_LOG = Services.prefs.getBoolPref(PREF_DEBUG_LOG);
-} catch (ex) {
-  // Ignore errors
-}
+var DEBUG_LOG = Services.prefs.getBoolPref(PREF_DEBUG_LOG, false);
 Services.prefs.addObserver(PREF_DEBUG_LOG, function() {
   DEBUG_LOG = Services.prefs.getBoolPref(PREF_DEBUG_LOG);
 }, false);
@@ -360,12 +351,7 @@ this.AsyncShutdown = {
    * Access function getPhase. For testing purposes only.
    */
   get _getPhase() {
-    let accepted = false;
-    try {
-      accepted = Services.prefs.getBoolPref("toolkit.asyncshutdown.testing");
-    } catch (ex) {
-      // Ignore errors
-    }
+    let accepted = Services.prefs.getBoolPref("toolkit.asyncshutdown.testing", false);
     if (accepted) {
       return getPhase;
     }
@@ -464,12 +450,7 @@ function getPhase(topic) {
      * notification. For testing purposes only.
      */
     get _trigger() {
-      let accepted = false;
-      try {
-        accepted = Services.prefs.getBoolPref("toolkit.asyncshutdown.testing");
-      } catch (ex) {
-        // Ignore errors
-      }
+      let accepted = Services.prefs.getBoolPref("toolkit.asyncshutdown.testing", false);
       if (accepted) {
         return () => spinner.observe();
       }
diff --git a/toolkit/components/blocklist/nsBlocklistService.js b/toolkit/components/blocklist/nsBlocklistService.js
index 49033fc8f..b0115e25d 100644
--- a/toolkit/components/blocklist/nsBlocklistService.js
+++ b/toolkit/components/blocklist/nsBlocklistService.js
@@ -238,16 +238,7 @@ function getLocale() {
 
 /* Get the distribution pref values, from defaults only */
 function getDistributionPrefValue(aPrefName) {
-  var prefValue = "default";
-
-  var defaults = gPref.getDefaultBranch(null);
-  try {
-    prefValue = defaults.getCharPref(aPrefName);
-  } catch (e) {
-    // use default when pref not found
-  }
-
-  return prefValue;
+  return gPref.getDefaultBranch(null).getCharPref(aPrefName, "default");
 }
 
 /**
diff --git a/toolkit/components/jsdownloads/src/DownloadIntegration.jsm b/toolkit/components/jsdownloads/src/DownloadIntegration.jsm
index 305284749..a6875ec48 100644
--- a/toolkit/components/jsdownloads/src/DownloadIntegration.jsm
+++ b/toolkit/components/jsdownloads/src/DownloadIntegration.jsm
@@ -368,11 +368,7 @@ this.DownloadIntegration = {
    */
   getPreferredDownloadsDirectory: Task.async(function* () {
     let directoryPath = null;
-    let prefValue = 1;
-
-    try {
-      prefValue = Services.prefs.getIntPref("browser.download.folderList");
-    } catch(e) {}
+    let prefValue = Services.prefs.getIntPref("browser.download.folderList", 1);
 
     switch(prefValue) {
       case 0: // Desktop
diff --git a/toolkit/components/nsDefaultCLH.js b/toolkit/components/nsDefaultCLH.js
index a081bae49..affbf75ee 100644
--- a/toolkit/components/nsDefaultCLH.js
+++ b/toolkit/components/nsDefaultCLH.js
@@ -104,13 +104,7 @@ nsDefaultCLH.prototype = {
     // if the pref is missing, ignore the exception
     try {
       var chromeURI = prefs.getCharPref("toolkit.defaultChromeURI");
-
-      var flags = "chrome,dialog=no,all";
-      try {
-        flags = prefs.getCharPref("toolkit.defaultChromeFeatures");
-      }
-      catch (e) { }
-
+      var flags = prefs.getCharPref("toolkit.defaultChromeFeatures", "chrome,dialog=no,all");
       var wwatch = Components.classes["@mozilla.org/embedcomp/window-watcher;1"]
                             .getService(nsIWindowWatcher);
       wwatch.openWindow(null, chromeURI, "_blank",
diff --git a/toolkit/components/osfile/modules/osfile_async_front.jsm b/toolkit/components/osfile/modules/osfile_async_front.jsm
index 93c7e66d6..9f3b7fb21 100644
--- a/toolkit/components/osfile/modules/osfile_async_front.jsm
+++ b/toolkit/components/osfile/modules/osfile_async_front.jsm
@@ -239,10 +239,9 @@ var Scheduler = this.Scheduler = {
    * Prepare to kill the OS.File worker after a few seconds.
    */
   restartTimer: function(arg) {
-    let delay;
-    try {
-      delay = Services.prefs.getIntPref("osfile.reset_worker_delay");
-    } catch(e) {
+    let delay = Services.prefs.getIntPref("osfile.reset_worker_delay", 0);
+
+    if (!delay) {
       // Don't auto-shutdown if we don't have a delay preference set.
       return;
     }
@@ -469,42 +468,24 @@ const PREF_OSFILE_LOG = "toolkit.osfile.log";
 const PREF_OSFILE_LOG_REDIRECT = "toolkit.osfile.log.redirect";
 
 /**
- * Safely read a PREF_OSFILE_LOG preference.
- * Returns a value read or, in case of an error, oldPref or false.
- *
- * @param bool oldPref
- *        An optional value that the DEBUG flag was set to previously.
- */
-function readDebugPref(prefName, oldPref = false) {
-  let pref = oldPref;
-  try {
-    pref = Services.prefs.getBoolPref(prefName);
-  } catch (x) {
-    // In case of an error when reading a pref keep it as is.
-  }
-  // If neither pref nor oldPref were set, default it to false.
-  return pref;
-};
-
-/**
  * Listen to PREF_OSFILE_LOG changes and update gShouldLog flag
  * appropriately.
  */
 Services.prefs.addObserver(PREF_OSFILE_LOG,
   function prefObserver(aSubject, aTopic, aData) {
-    SharedAll.Config.DEBUG = readDebugPref(PREF_OSFILE_LOG, SharedAll.Config.DEBUG);
+    SharedAll.Config.DEBUG = Services.prefs.getBoolPref(PREF_OSFILE_LOG, SharedAll.Config.DEBUG);
     if (Scheduler.launched) {
       // Don't start the worker just to set this preference.
       Scheduler.post("SET_DEBUG", [SharedAll.Config.DEBUG]);
     }
   }, false);
-SharedAll.Config.DEBUG = readDebugPref(PREF_OSFILE_LOG, false);
+SharedAll.Config.DEBUG = Services.prefs.getBoolPref(PREF_OSFILE_LOG, false);
 
 Services.prefs.addObserver(PREF_OSFILE_LOG_REDIRECT,
   function prefObserver(aSubject, aTopic, aData) {
-    SharedAll.Config.TEST = readDebugPref(PREF_OSFILE_LOG_REDIRECT, OS.Shared.TEST);
+    SharedAll.Config.TEST = Services.prefs.getBoolPref(PREF_OSFILE_LOG_REDIRECT, OS.Shared.TEST);
   }, false);
-SharedAll.Config.TEST = readDebugPref(PREF_OSFILE_LOG_REDIRECT, false);
+SharedAll.Config.TEST = Services.prefs.getBoolPref(PREF_OSFILE_LOG_REDIRECT, false);
 
 
 /**
@@ -515,7 +496,7 @@ var nativeWheneverAvailable = true;
 const PREF_OSFILE_NATIVE = "toolkit.osfile.native";
 Services.prefs.addObserver(PREF_OSFILE_NATIVE,
   function prefObserver(aSubject, aTopic, aData) {
-    nativeWheneverAvailable = readDebugPref(PREF_OSFILE_NATIVE, nativeWheneverAvailable);
+    nativeWheneverAvailable = Services.prefs.getBoolPref(PREF_OSFILE_NATIVE, nativeWheneverAvailable);
   }, false);
 
 
@@ -557,12 +538,8 @@ Services.prefs.addObserver(PREF_OSFILE_TEST_SHUTDOWN_OBSERVER,
   function prefObserver() {
     // The temporary phase topic used to trigger the unclosed
     // phase warning.
-    let TOPIC = null;
-    try {
-      TOPIC = Services.prefs.getCharPref(
-        PREF_OSFILE_TEST_SHUTDOWN_OBSERVER);
-    } catch (x) {
-    }
+    let TOPIC = Services.prefs.getCharPref(PREF_OSFILE_TEST_SHUTDOWN_OBSERVER,
+                                           "");
     if (TOPIC) {
       // Generate a phase, add a blocker.
       // Note that this can work only if AsyncShutdown itself has been
diff --git a/toolkit/components/places/PlacesCategoriesStarter.js b/toolkit/components/places/PlacesCategoriesStarter.js
index 560bd486a..bab14db52 100644
--- a/toolkit/components/places/PlacesCategoriesStarter.js
+++ b/toolkit/components/places/PlacesCategoriesStarter.js
@@ -77,11 +77,8 @@ PlacesCategoriesStarter.prototype = {
         break;
       case "idle-daily":
         // Once a week run places.sqlite maintenance tasks.
-        let lastMaintenance = 0;
-        try {
-          lastMaintenance =
-            Services.prefs.getIntPref("places.database.lastMaintenance");
-        } catch (ex) {}
+        let lastMaintenance =
+            Services.prefs.getIntPref("places.database.lastMaintenance", 0);
         let nowSeconds = parseInt(Date.now() / 1000);
         if (lastMaintenance < nowSeconds - MAINTENANCE_INTERVAL_SECONDS) {
           PlacesDBUtils.maintenanceOnIdle();
diff --git a/toolkit/components/places/PlacesRemoteTabsAutocompleteProvider.jsm b/toolkit/components/places/PlacesRemoteTabsAutocompleteProvider.jsm
index d23d5bc6e..c3bc501eb 100644
--- a/toolkit/components/places/PlacesRemoteTabsAutocompleteProvider.jsm
+++ b/toolkit/components/places/PlacesRemoteTabsAutocompleteProvider.jsm
@@ -95,11 +95,7 @@ function observe(subject, topic, data) {
 
     case "nsPref:changed":
       if (data == PREF_SHOW_REMOTE_ICONS) {
-        try {
-          showRemoteIcons = Services.prefs.getBoolPref(PREF_SHOW_REMOTE_ICONS);
-        } catch (_) {
-          showRemoteIcons = true; // no such pref - default is to show the icons.
-        }
+        showRemoteIcons = Services.prefs.getBoolPref(PREF_SHOW_REMOTE_ICONS, true);
       }
       break;
 
diff --git a/toolkit/components/places/UnifiedComplete.js b/toolkit/components/places/UnifiedComplete.js
index ec5f91111..7b63e29bb 100644
--- a/toolkit/components/places/UnifiedComplete.js
+++ b/toolkit/components/places/UnifiedComplete.js
@@ -437,10 +437,7 @@ XPCOMUtils.defineLazyGetter(this, "Prefs", () => {
     store.suggestTyped = prefs.get(...PREF_SUGGEST_HISTORY_ONLYTYPED);
     store.suggestSearches = prefs.get(...PREF_SUGGEST_SEARCHES);
     store.maxCharsForSearchSuggestions = prefs.get(...PREF_MAX_CHARS_FOR_SUGGEST);
-    store.keywordEnabled = true;
-    try {
-      store.keywordEnabled = Services.prefs.getBoolPref("keyword.enabled");
-    } catch (ex) {}
+    store.keywordEnabled = Services.prefs.getBoolPref("keyword.enabled", true);
 
     // If history is not set, onlyTyped value should be ignored.
     if (!store.suggestHistory) {
diff --git a/toolkit/components/places/nsPlacesExpiration.js b/toolkit/components/places/nsPlacesExpiration.js
index 499934362..767a4d345 100644
--- a/toolkit/components/places/nsPlacesExpiration.js
+++ b/toolkit/components/places/nsPlacesExpiration.js
@@ -812,11 +812,8 @@ nsPlacesExpiration.prototype = {
 
   _loadPrefs: Task.async(function* () {
     // Get the user's limit, if it was set.
-    try {
-      // We want to silently fail since getIntPref throws if it does not exist,
-      // and use a default to fallback to.
-      this._urisLimit = this._prefBranch.getIntPref(PREF_MAX_URIS);
-    } catch (ex) { /* User limit not set */ }
+    this._urisLimit = this._prefBranch.getIntPref(PREF_MAX_URIS,
+                                                  PREF_MAX_URIS_NOTSET);
 
     if (this._urisLimit < 0) {
       // Some testing code expects a pref change to be synchronous, so
@@ -874,11 +871,8 @@ nsPlacesExpiration.prototype = {
                                 this._urisLimit);
 
     // Get the expiration interval value.
-    try {
-      // We want to silently fail since getIntPref throws if it does not exist,
-      // and use a default to fallback to.
-      this._interval = this._prefBranch.getIntPref(PREF_INTERVAL_SECONDS);
-    } catch (ex) { /* User interval not set */ }
+    this._interval = this._prefBranch.getIntPref(PREF_INTERVAL_SECONDS,
+                                                 PREF_INTERVAL_SECONDS_NOTSET);
     if (this._interval <= 0) {
       this._interval = PREF_INTERVAL_SECONDS_NOTSET;
     }
diff --git a/toolkit/components/places/tests/unit/test_000_frecency.js b/toolkit/components/places/tests/unit/test_000_frecency.js
index 0a7347a02..64ee86b59 100644
--- a/toolkit/components/places/tests/unit/test_000_frecency.js
+++ b/toolkit/components/places/tests/unit/test_000_frecency.js
@@ -56,14 +56,8 @@ var prefPrefix = "places.frecency.";
 function* task_initializeBucket(bucket) {
   let [cutoffName, weightName] = bucket;
   // get pref values
-  var weight = 0, cutoff = 0;
-  try {
-    weight = prefs.getIntPref(prefPrefix + weightName);
-  } catch (ex) {}
-  try {
-    cutoff = prefs.getIntPref(prefPrefix + cutoffName);
-  } catch (ex) {}
-
+  var weight = prefs.getIntPref(prefPrefix + weightName, 0);
+  var cutoff = prefs.getIntPref(prefPrefix + cutoffName, 0);
   if (cutoff < 1)
     return;
 
diff --git a/toolkit/components/printing/content/printPageSetup.js b/toolkit/components/printing/content/printPageSetup.js
index 31eb1bdd3..6bcd97207 100644
--- a/toolkit/components/printing/content/printPageSetup.js
+++ b/toolkit/components/printing/content/printPageSetup.js
@@ -65,14 +65,7 @@ function initDialog()
 // ---------------------------------------------------
 function isListOfPrinterFeaturesAvailable()
 {
-  var has_printerfeatures = false;
-
-  try {
-    has_printerfeatures = gPrefs.getBoolPref("print.tmp.printerfeatures." + gPrintSettings.printerName + ".has_special_printerfeatures");
-  } catch (ex) {
-  }
-
-  return has_printerfeatures;
+  return gPrefs.getBoolPref("print.tmp.printerfeatures." + gPrintSettings.printerName + ".has_special_printerfeatures", false);
 }
 
 // ---------------------------------------------------
diff --git a/toolkit/components/printing/content/printdialog.js b/toolkit/components/printing/content/printdialog.js
index e5a38ddce..f9ed94bad 100644
--- a/toolkit/components/printing/content/printdialog.js
+++ b/toolkit/components/printing/content/printdialog.js
@@ -79,15 +79,7 @@ function stripTrailingWhitespace(element)
 // ---------------------------------------------------
 function getPrinterDescription(printerName)
 {
-  var s = "";
-
-  try {
-    /* This may not work with non-ASCII test (see bug 235763 comment #16) */
-    s = gPrefs.getCharPref("print.printer_" + printerName + ".printer_description")
-  } catch (e) {
-  }
-
-  return s;
+  return gPrefs.getCharPref("print.printer_" + printerName + ".printer_description", "")
 }
 
 // ---------------------------------------------------
diff --git a/toolkit/components/printing/content/printjoboptions.js b/toolkit/components/printing/content/printjoboptions.js
index 26f3ffd85..098358940 100644
--- a/toolkit/components/printing/content/printjoboptions.js
+++ b/toolkit/components/printing/content/printjoboptions.js
@@ -33,14 +33,7 @@ function checkDouble(element, maxVal)
 // ---------------------------------------------------
 function isListOfPrinterFeaturesAvailable()
 {
-  var has_printerfeatures = false;
-
-  try {
-    has_printerfeatures = gPrefs.getBoolPref("print.tmp.printerfeatures." + gPrintSettings.printerName + ".has_special_printerfeatures");
-  } catch (ex) {
-  }
-
-  return has_printerfeatures;
+  return gPrefs.getBoolPref("print.tmp.printerfeatures." + gPrintSettings.printerName + ".has_special_printerfeatures", false);
 }
 
 // ---------------------------------------------------
diff --git a/toolkit/components/search/current/nsSearchService.js b/toolkit/components/search/current/nsSearchService.js
index 2a8601078..db90e5150 100644
--- a/toolkit/components/search/current/nsSearchService.js
+++ b/toolkit/components/search/current/nsSearchService.js
@@ -390,12 +390,7 @@ function isPartnerBuild() {
 
 // Method to determine if we should be using geo-specific defaults
 function geoSpecificDefaultsEnabled() {
-  let geoSpecificDefaults = false;
-  try {
-    geoSpecificDefaults = Services.prefs.getBoolPref("browser.search.geoSpecificDefaults");
-  } catch (e) {}
-
-  return geoSpecificDefaults;
+  return Services.prefs.getBoolPref("browser.search.geoSpecificDefaults", false);
 }
 
 // Some notes on countryCode and region prefs:
@@ -500,11 +495,7 @@ function isUSTimezone() {
 // If it fails we don't touch that pref so isUS() does its normal thing.
 var ensureKnownCountryCode = Task.async(function* (ss) {
   // If we have a country-code already stored in our prefs we trust it.
-  let countryCode;
-  try {
-    countryCode = Services.prefs.getCharPref("browser.search.countryCode");
-  } catch (e) {}
-
+  let countryCode = Services.prefs.getCharPref("browser.search.countryCode", "");
   if (!countryCode) {
     // We don't have it cached, so fetch it. fetchCountryCode() will call
     // storeCountryCode if it gets a result (even if that happens after the
@@ -726,10 +717,7 @@ var fetchRegionDefault = (ss) => new Promise(resolve => {
 
   // Append the optional cohort value.
   const cohortPref = "browser.search.cohort";
-  let cohort;
-  try {
-    cohort = Services.prefs.getCharPref(cohortPref);
-  } catch (e) {}
+  let cohort = Services.prefs.getCharPref(cohortPref, "");
   if (cohort)
     endpoint += "/" + cohort;
 
@@ -993,11 +981,8 @@ function QueryParameter(aName, aValue, aPurpose) {
 function ParamSubstitution(aParamValue, aSearchTerms, aEngine) {
   var value = aParamValue;
 
-  var distributionID = Services.appinfo.distributionID;
-  try {
-    distributionID = Services.prefs.getCharPref(BROWSER_SEARCH_PREF + "distributionID");
-  }
-  catch (ex) { }
+  var distributionID = Services.prefs.getCharPref(BROWSER_SEARCH_PREF + "distributionID",
+                                                Services.appinfo.distributionID || "");
   var official = MOZ_OFFICIAL;
   try {
     if (Services.prefs.getBoolPref(BROWSER_SEARCH_PREF + "official"))
diff --git a/toolkit/components/search/orginal/nsSearchService.js b/toolkit/components/search/orginal/nsSearchService.js
index 5b5ce7a57..1cec5f966 100644
--- a/toolkit/components/search/orginal/nsSearchService.js
+++ b/toolkit/components/search/orginal/nsSearchService.js
@@ -418,12 +418,7 @@ function isPartnerBuild() {
 
 // Method to determine if we should be using geo-specific defaults
 function geoSpecificDefaultsEnabled() {
-  let geoSpecificDefaults = false;
-  try {
-    geoSpecificDefaults = Services.prefs.getBoolPref("browser.search.geoSpecificDefaults");
-  } catch(e) {}
-
-  return geoSpecificDefaults;
+  return Services.prefs.getBoolPref("browser.search.geoSpecificDefaults", false);
 }
 
 // Some notes on countryCode and region prefs:
@@ -528,11 +523,7 @@ function isUSTimezone() {
 // If it fails we don't touch that pref so isUS() does its normal thing.
 var ensureKnownCountryCode = Task.async(function* () {
   // If we have a country-code already stored in our prefs we trust it.
-  let countryCode;
-  try {
-    countryCode = Services.prefs.getCharPref("browser.search.countryCode");
-  } catch(e) {}
-
+  let countryCode = Services.prefs.getCharPref("browser.search.countryCode", "");
   if (!countryCode) {
     // We don't have it cached, so fetch it. fetchCountryCode() will call
     // storeCountryCode if it gets a result (even if that happens after the
@@ -732,10 +723,7 @@ var fetchRegionDefault = () => new Promise(resolve => {
 
   // Append the optional cohort value.
   const cohortPref = "browser.search.cohort";
-  let cohort;
-  try {
-    cohort = Services.prefs.getCharPref(cohortPref);
-  } catch(e) {}
+  let cohort = Services.prefs.getCharPref(cohortPref, "");
   if (cohort)
     endpoint += "/" + cohort;
 
@@ -1034,11 +1022,8 @@ function QueryParameter(aName, aValue, aPurpose) {
 function ParamSubstitution(aParamValue, aSearchTerms, aEngine) {
   var value = aParamValue;
 
-  var distributionID = MOZ_DISTRIBUTION_ID;
-  try {
-    distributionID = Services.prefs.getCharPref(BROWSER_SEARCH_PREF + "distributionID");
-  }
-  catch (ex) { }
+  var distributionID = Services.prefs.getCharPref(BROWSER_SEARCH_PREF + "distributionID",
+                                                MOZ_DISTRIBUTION_ID || "");
   var official = MOZ_OFFICIAL;
   try {
     if (Services.prefs.getBoolPref(BROWSER_SEARCH_PREF + "official"))
diff --git a/toolkit/components/telemetry/UITelemetry.jsm b/toolkit/components/telemetry/UITelemetry.jsm
index bd7a34b72..231b52e23 100644
--- a/toolkit/components/telemetry/UITelemetry.jsm
+++ b/toolkit/components/telemetry/UITelemetry.jsm
@@ -36,11 +36,7 @@ this.UITelemetry = {
     Services.obs.addObserver(this, "profile-before-change", false);
 
     // Pick up the current value.
-    try {
-      this._enabled = Services.prefs.getBoolPref(PREF_ENABLED);
-    } catch (e) {
-      this._enabled = false;
-    }
+    this._enabled = Services.prefs.getBoolPref(PREF_ENABLED, false);
 
     return this._enabled;
   },
diff --git a/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js b/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js
index ba4bf225a..5d462c90d 100644
--- a/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js
+++ b/toolkit/components/url-classifier/nsUrlClassifierHashCompleter.js
@@ -20,12 +20,7 @@ Cu.import("resource://gre/modules/NetUtil.jsm");
 
 // Log only if browser.safebrowsing.debug is true
 function log(...stuff) {
-  let logging = null;
-  try {
-    logging = Services.prefs.getBoolPref("browser.safebrowsing.debug");
-  } catch(e) {
-    return;
-  }
+  let logging = Services.prefs.getBoolPref("browser.safebrowsing.debug", false);
   if (!logging) {
     return;
   }
diff --git a/toolkit/components/urlformatter/tests/unit/test_urlformatter.js b/toolkit/components/urlformatter/tests/unit/test_urlformatter.js
index 393b0dc33..6f218822a 100644
--- a/toolkit/components/urlformatter/tests/unit/test_urlformatter.js
+++ b/toolkit/components/urlformatter/tests/unit/test_urlformatter.js
@@ -27,11 +27,9 @@ function run_test() {
                 QueryInterface(Ci.nsIXULRuntime);
   var abi = macutils && macutils.isUniversalBinary ? "Universal-gcc3" : appInfo.XPCOMABI;
 
-  let channel = "default";
   let defaults = prefs.QueryInterface(Ci.nsIPrefService).getDefaultBranch(null);
-  try {
-    channel = defaults.getCharPref("app.update.channel");
-  } catch (e) {}
+  let channel = defaults.getCharPref("app.update.channel", "default");
+
   // Set distribution values.
   defaults.setCharPref("distribution.id", "bacon");
   defaults.setCharPref("distribution.version", "1.0");
diff --git a/toolkit/content/widgets/browser.xml b/toolkit/content/widgets/browser.xml
index 9c72e86d8..11ed998cc 100644
--- a/toolkit/content/widgets/browser.xml
+++ b/toolkit/content/widgets/browser.xml
@@ -19,14 +19,7 @@
             if (this.getAttribute("autoscroll") == "false")
               return false;
 
-            var enabled = true;
-            try {
-              enabled = this.mPrefs.getBoolPref("general.autoScroll");
-            }
-            catch (ex) {
-            }
-
-            return enabled;
+            return this.mPrefs.getBoolPref("general.autoScroll", true);
           ]]>
         </getter>
       </property>
@@ -1427,18 +1420,8 @@
             return;
 
           // Toggle browse with caret mode
-          var browseWithCaretOn = false;
-          var warn = true;
-
-          try {
-            warn = this.mPrefs.getBoolPref(kPrefWarnOnEnable);
-          } catch (ex) {
-          }
-
-          try {
-            browseWithCaretOn = this.mPrefs.getBoolPref(kPrefCaretBrowsingOn);
-          } catch (ex) {
-          }
+          var browseWithCaretOn = this.mPrefs.getBoolPref(kPrefCaretBrowsingOn, false);
+          var warn = this.mPrefs.getBoolPref(kPrefWarnOnEnable, true);
           if (warn && !browseWithCaretOn) {
             var checkValue = {value:false};
             var promptService = Components.classes["@mozilla.org/embedcomp/prompt-service;1"]
diff --git a/toolkit/content/widgets/preferences.xml b/toolkit/content/widgets/preferences.xml
index 9fb2ac7ea..11de03246 100644
--- a/toolkit/content/widgets/preferences.xml
+++ b/toolkit/content/widgets/preferences.xml
@@ -893,12 +893,8 @@
         <![CDATA[
           var psvc = Components.classes["@mozilla.org/preferences-service;1"]
                                .getService(Components.interfaces.nsIPrefBranch);
-          var animate = /Mac/.test(navigator.platform);
-          try {
-            animate = psvc.getBoolPref("browser.preferences.animateFadeIn");
-          }
-          catch (e) { }
-          return animate;
+          return psvc.getBoolPref("browser.preferences.animateFadeIn",
+                                       /Mac/.test(navigator.platform));
         ]]>
         </getter>
       </property>
diff --git a/toolkit/content/widgets/scrollbox.xml b/toolkit/content/widgets/scrollbox.xml
index ff57a5911..219b7cb5e 100644
--- a/toolkit/content/widgets/scrollbox.xml
+++ b/toolkit/content/widgets/scrollbox.xml
@@ -80,13 +80,8 @@
       <property name="scrollIncrement" readonly="true">
         <getter><![CDATA[
           if (this._scrollIncrement === null) {
-            try {
-              this._scrollIncrement = this._prefBranch
-                                          .getIntPref("toolkit.scrollbox.scrollIncrement");
-            }
-            catch (ex) {
-              this._scrollIncrement = 20;
-            }
+            this._scrollIncrement = this._prefBranch
+                                        .getIntPref("toolkit.scrollbox.scrollIncrement", 20);
           }
           return this._scrollIncrement;
         ]]></getter>
@@ -99,13 +94,8 @@
             if (this.hasAttribute("smoothscroll")) {
               this._smoothScroll = (this.getAttribute("smoothscroll") == "true");
             } else {
-              try {
-                this._smoothScroll = this._prefBranch
-                                         .getBoolPref("toolkit.scrollbox.smoothScroll");
-              }
-              catch (ex) {
-                this._smoothScroll = true;
-              }
+              this._smoothScroll = this._prefBranch
+                                       .getBoolPref("toolkit.scrollbox.smoothScroll", true);
             }
           }
           return this._smoothScroll;
@@ -737,12 +727,9 @@
     </content>
     <implementation implements="nsITimerCallback, nsIDOMEventListener">
       <constructor><![CDATA[
-        try {
-          this._scrollDelay = this._prefBranch
-                                  .getIntPref("toolkit.scrollbox.clickToScroll.scrollDelay");
-        }
-        catch (ex) {
-        }
+        this._scrollDelay = this._prefBranch
+                                .getIntPref("toolkit.scrollbox.clickToScroll.scrollDelay",
+                                            this._scrollDelay);
       ]]></constructor>
 
       <destructor><![CDATA[
diff --git a/toolkit/modules/NewTabUtils.jsm b/toolkit/modules/NewTabUtils.jsm
index 548d87dda..35e38156f 100644
--- a/toolkit/modules/NewTabUtils.jsm
+++ b/toolkit/modules/NewTabUtils.jsm
@@ -119,18 +119,14 @@ LinksStorage.prototype = {
 
   get _storedVersion() {
     if (this.__storedVersion === undefined) {
-      try {
-        this.__storedVersion =
-          Services.prefs.getIntPref("browser.newtabpage.storageVersion");
-      } catch (ex) {
-        // The storage version is unknown, so either:
-        // - it's a new profile
-        // - it's a profile where versioning information got lost
-        // In this case we still run through all of the valid migrations,
-        // starting from 1, as if it was a downgrade.  As previously stated the
-        // migrations should already support running on an updated store.
-        this.__storedVersion = 1;
-      }
+      // The storage version is unknown, so either:
+      // - it's a new profile
+      // - it's a profile where versioning information got lost
+      // In this case we still run through all of the valid migrations,
+      // starting from 1, as if it was a downgrade.  As previously stated the
+      // migrations should already support running on an updated store.
+      this.__storedVersion =
+        Services.prefs.getIntPref("browser.newtabpage.storageVersion", 1);
     }
     return this.__storedVersion;
   },
diff --git a/toolkit/modules/PermissionsUtils.jsm b/toolkit/modules/PermissionsUtils.jsm
index dfed76f0c..4bf43a3ec 100644
--- a/toolkit/modules/PermissionsUtils.jsm
+++ b/toolkit/modules/PermissionsUtils.jsm
@@ -16,10 +16,7 @@ function importPrefBranch(aPrefBranch, aPermission, aAction) {
   let list = Services.prefs.getChildList(aPrefBranch, {});
 
   for (let pref of list) {
-    let origins = "";
-    try {
-      origins = Services.prefs.getCharPref(pref);
-    } catch (e) {}
+    let origins = Services.prefs.getCharPref(pref, "");
 
     if (!origins)
       continue;
diff --git a/toolkit/modules/UpdateUtils.jsm b/toolkit/modules/UpdateUtils.jsm
index e92b1b797..fed7c7637 100644
--- a/toolkit/modules/UpdateUtils.jsm
+++ b/toolkit/modules/UpdateUtils.jsm
@@ -31,13 +31,9 @@ this.UpdateUtils = {
    *        Whether or not to include the partner bits. Default: true.
    */
   getUpdateChannel(aIncludePartners = true) {
-    let channel = AppConstants.MOZ_UPDATE_CHANNEL;
+    let channel = defaults.getCharPref("app.update.channel",
+                                       AppConstants.MOZ_UPDATE_CHANNEL);
     let defaults = Services.prefs.getDefaultBranch(null);
-    try {
-      channel = defaults.getCharPref("app.update.channel");
-    } catch (e) {
-      // use default value when pref not found
-    }
 
     if (aIncludePartners) {
       try {
@@ -93,15 +89,7 @@ this.UpdateUtils = {
 
 /* Get the distribution pref values, from defaults only */
 function getDistributionPrefValue(aPrefName) {
-  var prefValue = "default";
-
-  try {
-    prefValue = Services.prefs.getDefaultBranch(null).getCharPref(aPrefName);
-  } catch (e) {
-    // use default when pref not found
-  }
-
-  return prefValue;
+  return prefValue = Services.prefs.getDefaultBranch(null).getCharPref(aPrefName, "default");
 }
 
 /**
diff --git a/toolkit/modules/secondscreen/SimpleServiceDiscovery.jsm b/toolkit/modules/secondscreen/SimpleServiceDiscovery.jsm
index cf9617ea1..4abc93ad1 100644
--- a/toolkit/modules/secondscreen/SimpleServiceDiscovery.jsm
+++ b/toolkit/modules/secondscreen/SimpleServiceDiscovery.jsm
@@ -186,10 +186,7 @@ var SimpleServiceDiscovery = {
   },
 
   _searchFixedDevices: function _searchFixedDevices() {
-    let fixedDevices = null;
-    try {
-      fixedDevices = Services.prefs.getCharPref("browser.casting.fixedDevices");
-    } catch (e) {}
+    let fixedDevices = Services.prefs.getCharPref("browser.casting.fixedDevices", "");
 
     if (!fixedDevices) {
       return;
diff --git a/toolkit/mozapps/downloads/nsHelperAppDlg.js b/toolkit/mozapps/downloads/nsHelperAppDlg.js
index 58697cc77..27c0fede0 100644
--- a/toolkit/mozapps/downloads/nsHelperAppDlg.js
+++ b/toolkit/mozapps/downloads/nsHelperAppDlg.js
@@ -253,10 +253,7 @@ nsUnknownContentTypeDialog.prototype = {
       if (!aForcePrompt) {
         // Check to see if the user wishes to auto save to the default download
         // folder without prompting. Note that preference might not be set.
-        let autodownload = false;
-        try {
-          autodownload = prefs.getBoolPref(PREF_BD_USEDOWNLOADDIR);
-        } catch (e) { }
+        let autodownload = prefs.getBoolPref(PREF_BD_USEDOWNLOADDIR, false);
 
         if (autodownload) {
           // Retrieve the user's default download directory
diff --git a/toolkit/mozapps/extensions/AddonManager.jsm b/toolkit/mozapps/extensions/AddonManager.jsm
index 4cd2c3d0a..a48e0034f 100644
--- a/toolkit/mozapps/extensions/AddonManager.jsm
+++ b/toolkit/mozapps/extensions/AddonManager.jsm
@@ -135,12 +135,7 @@ var PrefObserver = {
         Services.obs.removeObserver(this, "xpcom-shutdown");
       }
       else if (aTopic == NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) {
-        let debugLogEnabled = false;
-        try {
-          debugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED);
-        }
-        catch (e) {
-        }
+        let debugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED, false);
         if (debugLogEnabled) {
           parentLogger.level = Log.Level.Debug;
         }
@@ -791,11 +786,7 @@ var AddonManagerInternal = {
       }
       catch (e) { }
 
-      let oldPlatformVersion = null;
-      try {
-        oldPlatformVersion = Services.prefs.getCharPref(PREF_EM_LAST_PLATFORM_VERSION);
-      }
-      catch (e) { }
+      let oldPlatformVersion = Services.prefs.getCharPref(PREF_EM_LAST_PLATFORM_VERSION, "");
 
       if (appChanged !== false) {
         logger.debug("Application has been upgraded");
@@ -808,40 +799,30 @@ var AddonManagerInternal = {
         this.validateBlocklist();
       }
 
-      try {
-        gCheckCompatibility = Services.prefs.getBoolPref(PREF_EM_CHECK_COMPATIBILITY);
-      } catch (e) {}
+      gCheckCompatibility = Services.prefs.getBoolPref(PREF_EM_CHECK_COMPATIBILITY,
+                                                       gCheckCompatibility);
       Services.prefs.addObserver(PREF_EM_CHECK_COMPATIBILITY, this, false);
 
-      try {
-        gStrictCompatibility = Services.prefs.getBoolPref(PREF_EM_STRICT_COMPATIBILITY);
-      } catch (e) {}
+      gStrictCompatibility = Services.prefs.getBoolPref(PREF_EM_STRICT_COMPATIBILITY,
+                                                        gStrictCompatibility);
       Services.prefs.addObserver(PREF_EM_STRICT_COMPATIBILITY, this, false);
 
-      try {
-        let defaultBranch = Services.prefs.getDefaultBranch("");
-        gCheckUpdateSecurityDefault = defaultBranch.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY);
-      } catch(e) {}
+      let defaultBranch = Services.prefs.getDefaultBranch("");
+      gCheckUpdateSecurityDefault = defaultBranch.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY,
+                                                              gCheckUpdateSecurityDefault);
 
-      try {
-        gCheckUpdateSecurity = Services.prefs.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY);
-      } catch (e) {}
+      gCheckUpdateSecurity = Services.prefs.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY,
+                                                        gCheckUpdateSecurity);
       Services.prefs.addObserver(PREF_EM_CHECK_UPDATE_SECURITY, this, false);
 
-      try {
-        gUpdateEnabled = Services.prefs.getBoolPref(PREF_EM_UPDATE_ENABLED);
-      } catch (e) {}
+      gUpdateEnabled = Services.prefs.getBoolPref(PREF_EM_UPDATE_ENABLED, gUpdateEnabled);
       Services.prefs.addObserver(PREF_EM_UPDATE_ENABLED, this, false);
 
-      try {
-        gAutoUpdateDefault = Services.prefs.getBoolPref(PREF_EM_AUTOUPDATE_DEFAULT);
-      } catch (e) {}
+      gAutoUpdateDefault = Services.prefs.getBoolPref(PREF_EM_AUTOUPDATE_DEFAULT,
+                                                      gAutoUpdateDefault);
       Services.prefs.addObserver(PREF_EM_AUTOUPDATE_DEFAULT, this, false);
 
-      let defaultProvidersEnabled = true;
-      try {
-        defaultProvidersEnabled = Services.prefs.getBoolPref(PREF_DEFAULT_PROVIDERS_ENABLED);
-      } catch (e) {}
+      let defaultProvidersEnabled = Services.prefs.getBoolPref(PREF_DEFAULT_PROVIDERS_ENABLED, true);
       AddonManagerPrivate.recordSimpleMeasure("default_providers", defaultProvidersEnabled);
 
       // Ensure all default providers have had a chance to register themselves
@@ -1167,11 +1148,7 @@ var AddonManagerInternal = {
     switch (aData) {
       case PREF_EM_CHECK_COMPATIBILITY: {
         let oldValue = gCheckCompatibility;
-        try {
-          gCheckCompatibility = Services.prefs.getBoolPref(PREF_EM_CHECK_COMPATIBILITY);
-        } catch(e) {
-          gCheckCompatibility = true;
-        }
+        gCheckCompatibility = Services.prefs.getBoolPref(PREF_EM_CHECK_COMPATIBILITY, true);
 
         this.callManagerListeners("onCompatibilityModeChanged");
 
@@ -1182,11 +1159,7 @@ var AddonManagerInternal = {
       }
       case PREF_EM_STRICT_COMPATIBILITY: {
         let oldValue = gStrictCompatibility;
-        try {
-          gStrictCompatibility = Services.prefs.getBoolPref(PREF_EM_STRICT_COMPATIBILITY);
-        } catch(e) {
-          gStrictCompatibility = true;
-        }
+        gStrictCompatibility = Services.prefs.getBoolPref(PREF_EM_STRICT_COMPATIBILITY, true);
 
         this.callManagerListeners("onCompatibilityModeChanged");
 
@@ -1197,11 +1170,7 @@ var AddonManagerInternal = {
       }
       case PREF_EM_CHECK_UPDATE_SECURITY: {
         let oldValue = gCheckUpdateSecurity;
-        try {
-          gCheckUpdateSecurity = Services.prefs.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY);
-        } catch(e) {
-          gCheckUpdateSecurity = true;
-        }
+        gCheckUpdateSecurity = Services.prefs.getBoolPref(PREF_EM_CHECK_UPDATE_SECURITY, true);
 
         this.callManagerListeners("onCheckUpdateSecurityChanged");
 
@@ -1212,22 +1181,14 @@ var AddonManagerInternal = {
       }
       case PREF_EM_UPDATE_ENABLED: {
         let oldValue = gUpdateEnabled;
-        try {
-          gUpdateEnabled = Services.prefs.getBoolPref(PREF_EM_UPDATE_ENABLED);
-        } catch(e) {
-          gUpdateEnabled = true;
-        }
+        gUpdateEnabled = Services.prefs.getBoolPref(PREF_EM_UPDATE_ENABLED, true);
 
         this.callManagerListeners("onUpdateModeChanged");
         break;
       }
       case PREF_EM_AUTOUPDATE_DEFAULT: {
         let oldValue = gAutoUpdateDefault;
-        try {
-          gAutoUpdateDefault = Services.prefs.getBoolPref(PREF_EM_AUTOUPDATE_DEFAULT);
-        } catch(e) {
-          gAutoUpdateDefault = true;
-        }
+        gAutoUpdateDefault = Services.prefs.getBoolPref(PREF_EM_AUTOUPDATE_DEFAULT, true);
 
         this.callManagerListeners("onUpdateModeChanged");
         break;
diff --git a/toolkit/mozapps/extensions/DeferredSave.jsm b/toolkit/mozapps/extensions/DeferredSave.jsm
index 89f82b265..f1537fe4b 100644
--- a/toolkit/mozapps/extensions/DeferredSave.jsm
+++ b/toolkit/mozapps/extensions/DeferredSave.jsm
@@ -64,12 +64,7 @@ var PrefObserver = {
      Services.obs.removeObserver(this, "xpcom-shutdown");
    }
    else if (aTopic == NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) {
-     let debugLogEnabled = false;
-     try {
-       debugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED);
-     }
-     catch (e) {
-     }
+     let debugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED, false);
      if (debugLogEnabled) {
        parentLogger.level = Log.Level.Debug;
      }
diff --git a/toolkit/mozapps/extensions/GMPUtils.jsm b/toolkit/mozapps/extensions/GMPUtils.jsm
index 9e41a7a61..a199b4d86 100644
--- a/toolkit/mozapps/extensions/GMPUtils.jsm
+++ b/toolkit/mozapps/extensions/GMPUtils.jsm
@@ -154,13 +154,7 @@ this.GMPPrefs = {
   get: function(aKey, aDefaultValue, aPlugin) {
     if (aKey === this.KEY_APP_DISTRIBUTION ||
         aKey === this.KEY_APP_DISTRIBUTION_VERSION) {
-      let prefValue = "default";
-      try {
-        prefValue = Services.prefs.getDefaultBranch(null).getCharPref(aKey);
-      } catch (e) {
-        // use default when pref not found
-      }
-      return prefValue;
+      return Services.prefs.getDefaultBranch(null).getCharPref(aKey, "default");
     }
     return Preferences.get(this.getPrefKey(aKey, aPlugin), aDefaultValue);
   },
diff --git a/toolkit/mozapps/extensions/LightweightThemeManager.jsm b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
index 372a9f3b8..a4cbf3833 100644
--- a/toolkit/mozapps/extensions/LightweightThemeManager.jsm
+++ b/toolkit/mozapps/extensions/LightweightThemeManager.jsm
@@ -49,12 +49,7 @@ this.__defineGetter__("_prefs", function prefsGetter() {
 
 this.__defineGetter__("_maxUsedThemes", function maxUsedThemesGetter() {
   delete this._maxUsedThemes;
-  try {
-    this._maxUsedThemes = _prefs.getIntPref("maxUsedThemes");
-  }
-  catch (e) {
-    this._maxUsedThemes = DEFAULT_MAX_USED_THEMES_COUNT;
-  }
+  this._maxUsedThemes = _prefs.getIntPref("maxUsedThemes", DEFAULT_MAX_USED_THEMES_COUNT);
   return this._maxUsedThemes;
 });
 
@@ -719,12 +714,8 @@ var _previewTimerCallback = {
 function _prefObserver(aSubject, aTopic, aData) {
   switch (aData) {
     case "maxUsedThemes":
-      try {
-        _maxUsedThemes = _prefs.getIntPref(aData);
-      }
-      catch (e) {
-        _maxUsedThemes = DEFAULT_MAX_USED_THEMES_COUNT;
-      }
+      _maxUsedThemes = _prefs.getIntPref(aData, DEFAULT_MAX_USED_THEMES_COUNT);
+
       // Update the theme list to remove any themes over the number we keep
       _updateUsedThemes(LightweightThemeManager.usedThemes);
       break;
diff --git a/toolkit/mozapps/extensions/internal/AddonLogging.jsm b/toolkit/mozapps/extensions/internal/AddonLogging.jsm
index f05a6fe6c..ffa92c791 100644
--- a/toolkit/mozapps/extensions/internal/AddonLogging.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonLogging.jsm
@@ -179,12 +179,7 @@ var PrefObserver = {
       Services.obs.removeObserver(this, "xpcom-shutdown");
     }
     else if (aTopic == NS_PREFBRANCH_PREFCHANGE_TOPIC_ID) {
-      try {
-        gDebugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED);
-      }
-      catch (e) {
-        gDebugLogEnabled = false;
-      }
+      gDebugLogEnabled = Services.prefs.getBoolPref(PREF_LOGGING_ENABLED, false);
     }
   }
 };
diff --git a/toolkit/mozapps/extensions/internal/AddonRepository.jsm b/toolkit/mozapps/extensions/internal/AddonRepository.jsm
index 76a7528c7..9750e9944 100644
--- a/toolkit/mozapps/extensions/internal/AddonRepository.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonRepository.jsm
@@ -486,14 +486,7 @@ this.AddonRepository = {
     }
 
     let preference = PREF_GETADDONS_CACHE_ENABLED;
-    let enabled = false;
-    try {
-      enabled = Services.prefs.getBoolPref(preference);
-    } catch(e) {
-      logger.warn("cacheEnabled: Couldn't get pref: " + preference);
-    }
-
-    return enabled;
+    return Services.prefs.getBoolPref(preference, false);
   },
 
   // A cache of the add-ons stored in the database
@@ -541,11 +534,7 @@ this.AddonRepository = {
 
   metadataAge: function() {
     let now = Math.round(Date.now() / 1000);
-
-    let lastUpdate = 0;
-    try {
-      lastUpdate = Services.prefs.getIntPref(PREF_METADATA_LASTUPDATE);
-    } catch (e) {}
+    let lastUpdate = Services.prefs.getIntPref(PREF_METADATA_LASTUPDATE, 0);
 
     // Handle clock jumps
     if (now < lastUpdate) {
@@ -555,10 +544,8 @@ this.AddonRepository = {
   },
 
   isMetadataStale: function AddonRepo_isMetadataStale() {
-    let threshold = DEFAULT_METADATA_UPDATETHRESHOLD_SEC;
-    try {
-      threshold = Services.prefs.getIntPref(PREF_METADATA_UPDATETHRESHOLD_SEC);
-    } catch (e) {}
+    let threshold = Services.prefs.getIntPref(PREF_METADATA_UPDATETHRESHOLD_SEC,
+                                              DEFAULT_METADATA_UPDATETHRESHOLD_SEC);
     return (this.metadataAge() > threshold);
   },
 
@@ -1543,10 +1530,8 @@ this.AddonRepository = {
 
   // Create url from preference, returning null if preference does not exist
   _formatURLPref: function AddonRepo_formatURLPref(aPreference, aSubstitutions) {
-    let url = null;
-    try {
-      url = Services.prefs.getCharPref(aPreference);
-    } catch(e) {
+    let url = Services.prefs.getCharPref(aPreference, "");
+    if (!url) {
       logger.warn("_formatURLPref: Couldn't get pref: " + aPreference);
       return null;
     }
@@ -1639,10 +1624,7 @@ var AddonDatabase = {
          // Create a blank addons.json file
          this._saveDBToDisk();
 
-         let dbSchema = 0;
-         try {
-           dbSchema = Services.prefs.getIntPref(PREF_GETADDONS_DB_SCHEMA);
-         } catch (e) {}
+         let dbSchema = Services.prefs.getIntPref(PREF_GETADDONS_DB_SCHEMA, 0);
 
          if (dbSchema < DB_MIN_JSON_SCHEMA) {
            let results = yield new Promise((resolve, reject) => {
diff --git a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
index c06dca1d5..a475f7f1f 100644
--- a/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
+++ b/toolkit/mozapps/extensions/internal/AddonUpdateChecker.jsm
@@ -608,12 +608,7 @@ function UpdateParser(aId, aUpdateKey, aUrl, aObserver) {
   this.observer = aObserver;
   this.url = aUrl;
 
-  let requireBuiltIn = true;
-  try {
-    requireBuiltIn = Services.prefs.getBoolPref(PREF_UPDATE_REQUIREBUILTINCERTS);
-  }
-  catch (e) {
-  }
+  let requireBuiltIn = Services.prefs.getBoolPref(PREF_UPDATE_REQUIREBUILTINCERTS, true);
 
   logger.debug("Requesting " + aUrl);
   try {
@@ -651,12 +646,7 @@ UpdateParser.prototype = {
     this.request = null;
     this._doneAt = new Error("place holder");
 
-    let requireBuiltIn = true;
-    try {
-      requireBuiltIn = Services.prefs.getBoolPref(PREF_UPDATE_REQUIREBUILTINCERTS);
-    }
-    catch (e) {
-    }
+    let requireBuiltIn = Services.prefs.getBoolPref(PREF_UPDATE_REQUIREBUILTINCERTS, true);
 
     try {
       CertUtils.checkCert(request.channel, !requireBuiltIn);
diff --git a/toolkit/mozapps/extensions/internal/XPIProviderUtils.js b/toolkit/mozapps/extensions/internal/XPIProviderUtils.js
index f2420bd1a..69d774e4a 100644
--- a/toolkit/mozapps/extensions/internal/XPIProviderUtils.js
+++ b/toolkit/mozapps/extensions/internal/XPIProviderUtils.js
@@ -1410,10 +1410,7 @@ this.XPIDatabase = {
     // when a lightweight theme is applied for example)
     text += "\r\n[ThemeDirs]\r\n";
 
-    let dssEnabled = false;
-    try {
-      dssEnabled = Services.prefs.getBoolPref(PREF_EM_DSS_ENABLED);
-    } catch (e) {}
+    let dssEnabled = Services.prefs.getBoolPref(PREF_EM_DSS_ENABLED, false);
 
     let themes = [];
     if (dssEnabled) {