When I start up Quest 5.8's desktop editor, I immediately get the error below:

System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
at TextAdventures.Quest.EditorControls.WFEditorTree.SetMenuEnabled(String key, Boolean enabled)
at TextAdventures.Quest.Editor.UpdateClipboardButtons()
at TextAdventures.Quest.Editor.ShowEditor(String key)
at TextAdventures.Quest.Editor.ctlTree_SelectionChanged(String key)
at TextAdventures.Quest.EditorControls.WFEditorTree.ChangeSelection(String key)
at TextAdventures.Quest.EditorControls.WFEditorTree.SelectCurrentTreeViewItem()
at TextAdventures.Quest.EditorControls.WFEditorTree.ctlTreeView_AfterSelect(Object sender, TreeViewEventArgs e)
at System.Windows.Forms.TreeView.OnAfterSelect(TreeViewEventArgs e)
at System.Windows.Forms.TreeView.TvnSelected(NMTREEVIEW* nmtv)
at System.Windows.Forms.TreeView.WmNotify(Message& m)
at System.Windows.Forms.TreeView.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

This also pops up every single time I click a button in the desktop editor, without fail. What does this mean and can it be fixed?

EDIT: I uninstalled and reinstalled Quest and that seemed to work. I am unsure of how - perhaps someone can still explain the error?

I was using Quest 5.7.2 previously, and it had no such errors.

Is this still a problem?
I haven't updated to 5.8 yet 'cause I'm a bit worried things like these will happen.

Could be the editor's "recent documents" list was corrupted; maybe the 5.8 installer couldn't handle one of the documents in it. Uninstalling and reinstalling could fix it by clearing the list.

Other people have had similar errors because of that.