From 8757548a3e5b5cc4d159d61eb4a12c7af1be548e Mon Sep 17 00:00:00 2001
From: Ascrod <32915892+Ascrod@users.noreply.github.com>
Date: Sat, 13 Apr 2019 11:22:15 -0400
Subject: Issue #991 Part 8: Toolkit everything else

---
 toolkit/content/widgets/browser.xml                | 23 +------
 toolkit/content/widgets/preferences.xml            |  8 +--
 toolkit/content/widgets/scrollbox.xml              | 27 ++------
 toolkit/modules/NewTabUtils.jsm                    | 20 +++---
 toolkit/modules/PermissionsUtils.jsm               |  5 +-
 toolkit/modules/UpdateUtils.jsm                    | 18 +----
 .../secondscreen/SimpleServiceDiscovery.jsm        |  5 +-
 toolkit/mozapps/downloads/nsHelperAppDlg.js        |  5 +-
 toolkit/mozapps/extensions/AddonManager.jsm        | 79 ++++++----------------
 toolkit/mozapps/extensions/DeferredSave.jsm        |  7 +-
 toolkit/mozapps/extensions/GMPUtils.jsm            |  8 +--
 .../mozapps/extensions/LightweightThemeManager.jsm | 15 +---
 .../mozapps/extensions/internal/AddonLogging.jsm   |  7 +-
 .../extensions/internal/AddonRepository.jsm        | 32 ++-------
 .../extensions/internal/AddonUpdateChecker.jsm     | 14 +---
 .../extensions/internal/XPIProviderUtils.js        |  5 +-
 16 files changed, 62 insertions(+), 216 deletions(-)

(limited to 'toolkit')

diff --git a/toolkit/content/widgets/browser.xml b/toolkit/content/widgets/browser.xml
index 9c72e86d88..11ed998cca 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 9fb2ac7ea1..11de032462 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 ff57a59114..219b7cb5e4 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 548d87ddaa..35e38156f9 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 dfed76f0c3..4bf43a3ec9 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 e92b1b797f..fed7c7637a 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 cf9617ea1e..4abc93ad1f 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 58697cc773..27c0fede0b 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 4cd2c3d0ae..a48e0034fd 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 89f82b2656..f1537fe4b6 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 9e41a7a614..a199b4d86b 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 372a9f3b81..a4cbf38332 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 f05a6fe6c3..ffa92c7915 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 76a7528c73..9750e99445 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 c06dca1d53..a475f7f1fa 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 f2420bd1ac..69d774e4a0 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) {
-- 
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