Fixes error when myroomjid is null.

audio_levels.js

         drawContext.drawImage(canvasCache, 0, 0);
 
         if(resourceJid === AudioLevels.LOCAL_LEVEL) {
+            if(!connection.emuc.myroomjid) {
+                return;
+            }
             resourceJid = Strophe.getResourceFromJid(connection.emuc.myroomjid);
         }
 

index.html

     <script src="toolbar.js?v=6"></script><!-- toolbar ui -->
     <script src="toolbar_toggler.js?v=2"></script>
     <script src="canvas_util.js?v=1"></script><!-- canvas drawing utils -->
-    <script src="audio_levels.js?v=3"></script><!-- audio levels plugin -->
+    <script src="audio_levels.js?v=4"></script><!-- audio levels plugin -->
     <script src="media_stream.js?v=2"></script><!-- media stream -->
     <script src="bottom_toolbar.js?v=6"></script><!-- media stream -->
     <script src="moderator.js?v=2"></script><!-- media stream -->