Issue 6477 - separate done and error callbacks in IFileSystem::Read

lib/prefs.js

Index: lib/prefs.js
diff --git a/lib/prefs.js b/lib/prefs.js
index 15b4efd174ae7e678013414be03fb7b8f64cf659..b9ac2c460c92bbb07b6f3803352c019810f38849 100644
--- a/lib/prefs.js
+++ b/lib/prefs.js
@@ -84,24 +84,27 @@ function defineProperty(key)
 
 function load()
 {
-  _fileSystem.read(prefsFileName, result =>
+  new Promise((resolve, reject) =>
   {
-    // prefs.json is expected to be missing, ignore errors reading file
-    if (!result.error)
+    _fileSystem.read(prefsFileName, resolve, reject);
+  }).then((result) =>
+  {
+    try
     {
-      try
-      {
-        let data = JSON.parse(result.content);
-        for (let key in data)
-          if (key in defaults)
-            values[key] = data[key];
-      }
-      catch (e)
-      {
-        Cu.reportError(e);
-      }
+      let data = JSON.parse(result.content);
+      for (let key in data)
+        if (key in defaults)
+          values[key] = data[key];
     }
-
+    catch (e)
+    {
+      Cu.reportError(e);
+    }
+  }).catch(() =>
+  {
+    // prefs.json is expected to be missing, ignore file reading errors
+  }).then(() =>
+  {
     Prefs.initialized = true;
     if (typeof Prefs._initListener == "function")
       Prefs._initListener();