MD Bookmarks: Prevent navigating to invalid folders

chrome/browser/resources/md_bookmarks/actions.js

 // Copyright 2017 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.
 
 /**
  * @fileoverview Module for functions which produce action objects. These are
  * listed in one place to document available actions and their parameters.
  */
 
 cr.define('bookmarks.actions', function() {
@@ skipping 79 matching lines @@
    */
   function refreshNodes(nodeMap) {
     return {
       name: 'refresh-nodes',
       nodes: nodeMap,
     };
   };
 
   /**
    * @param {string} id
-   * @return {!Action}
+   * @param {NodeMap} nodes Current node state. Can be ommitted in tests.
+   * @return {?Action}
    */
-  function selectFolder(id) {
-    assert(id != '0', 'Cannot select root folder');
+  function selectFolder(id, nodes) {
+    if (nodes && (id == ROOT_NODE_ID || !nodes[id] || nodes[id].url))

[calamity, 2017/05/02 08:27:15]

Hmm. Do you think it's reasonable to leave a console.warn() here? It would make
it easier to catch when things are going wildly wrong.

[tsergeant, 2017/05/03 02:57:31]

I've added the warning. There are some legitimate cases where this warning could
fire, though, so we might want to remove it later if it gets annoying.

[calamity, 2017/05/03 07:49:46]

Could you provide some examples?

[tsergeant, 2017/05/04 01:08:49]

The main one is if you delete a folder that you had previously visited and then
use the browser Back button to go back to chrome://bookmarks/?id=<deleted id>

+      return null;
+
     return {
       name: 'select-folder',
       id: id,
     };
   }
 
   /**
    * @param {string} id
    * @param {boolean} open
    * @return {!Action}
@@ skipping 92 matching lines @@
     moveBookmark: moveBookmark,
     refreshNodes: refreshNodes,
     removeBookmark: removeBookmark,
     reorderChildren: reorderChildren,
     selectFolder: selectFolder,
     selectItem: selectItem,
     setSearchResults: setSearchResults,
     setSearchTerm: setSearchTerm,
   };
 });