MD Bookmarks: Prevent navigating to invalid folders

chrome/browser/resources/md_bookmarks/actions.js

Index: chrome/browser/resources/md_bookmarks/actions.js
diff --git a/chrome/browser/resources/md_bookmarks/actions.js b/chrome/browser/resources/md_bookmarks/actions.js
index 11fd96e8c937921524ef2e88b5503962bd197b57..d104a31e4701bc0ae4a4ca068ca49c30dc90f20a 100644
--- a/chrome/browser/resources/md_bookmarks/actions.js
+++ b/chrome/browser/resources/md_bookmarks/actions.js
@@ -97,10 +97,13 @@ cr.define('bookmarks.actions', function() {
 
   /**
    * @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,