No longer throws an exception when displaying a tag cloud widget in a non-forum node type, e.g. a search forum.
Our solution is to just not display the tag cloud widget unless it's being passed an XF:Forum entity. Previously it'd always throw an exception if it was passed an XF:SearchForum entity. For our purposes that seems reasonable, since there's no good reason to display a tag cloud widget when the threads are coming from all over the place.