Bug 1010531 - Prevent async callback from throwing when a callback is made with an error. r=rnewman

services/common/async.js

@@ -63,6 +63,12 @@ this.Async = {
   /**
    * Create a sync callback that remembers state, in particular whether it has
    * been called.
+   * The returned callback can be called directly passing an optional arg which
+   * will be returned by waitForSyncCallback().  The callback also has a
+   * .throw() method, which takes an error object and will cause
+   * waitForSyncCallback to fail with the error object thrown as an exception
+   * (but note that the .throw method *does not* itself throw - it just causes
+   * the wait function to throw).
    */
   makeSyncCallback: function makeSyncCallback() {
     // The main callback remembers the value it was passed, and that it got data.
@@ -79,9 +85,6 @@ this.Async = {
     onComplete.throw = function onComplete_throw(data) {
       onComplete.state = CB_FAIL;
       onComplete.value = data;
-
-      // Cause the caller to get an exception and stop execution.
-      throw data;
     };
 
     return onComplete;
@@ -136,7 +139,8 @@ this.Async = {
     function callback(error, ret) {
       if (error)
         cb.throw(error);
-      cb(ret);
+      else
+        cb(ret);
     }
     callback.wait = function() Async.waitForSyncCallback(cb);
     return callback;

services/sync/modules/resource.js

@@ -380,7 +380,8 @@ Resource.prototype = {
     function callback(error, ret) {
       if (error)
         cb.throw(error);
-      cb(ret);
+      else
+        cb(ret);
     }
 
     // The channel listener might get a failure code