Handle a non-existing promise when receiving a signin error in the SupervisedUserListData.

chrome/browser/resources/options/supervised_user_list_data.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('options', function() {
   /**
    * SupervisedUserListData class.
    * Handles requests for retrieving a list of existing supervised users which
    * are supervised by the current profile. For each request a promise is
    * returned, which is cached in order to reuse the retrieved supervised users
@@ skipping 13 matching lines @@
    *     Each object is of the form:
    *       supervisedUser = {
    *         id: "Supervised User ID",
    *         name: "Supervised User Name",
    *         iconURL: "chrome://path/to/icon/image",
    *         onCurrentDevice: true or false,
    *         needAvatar: true or false
    *       }
    * @private
    */
-  SupervisedUserListData.prototype.receiveExistingSupervisedUsers_ = function(
-    supervisedUsers) {
+  SupervisedUserListData.prototype.receiveExistingSupervisedUsers_ =
+      function(supervisedUsers) {
     if (!this.promise_) {
       this.onDataChanged_(supervisedUsers);
       return;
     }
     this.resolve_(supervisedUsers);
   };
 
   /**
    * Called when there is a signin error when retrieving the list of supervised
    * users. Rejects the promise and resets the cached promise to null.
    * @private
    */
   SupervisedUserListData.prototype.onSigninError_ = function() {
-    assert(this.promise_);
+    if (!this.promise_) {
+      return;
+    }
     this.reject_();
     this.resetPromise_();
   };
 
   /**
    * Handles the request for the list of existing supervised users by returning
    * a promise for the requested data. If there is no cached promise yet, a new
    * one will be created.
    * @return {Promise} The promise containing the list of supervised users.
    * @private
@@ skipping 84 matching lines @@
       var instance = SupervisedUserListData.getInstance();
       return instance[name + '_'].apply(instance, arguments);
     };
   });
 
   // Export
   return {
     SupervisedUserListData: SupervisedUserListData,
   };
 });