uncaught exception in webIDE when running firefox os simulator

I was running ffos 2.0 simulator in webIDE and testing world-clock example as given in http://ift.tt/1aFegb6 on windows 7 machine. This throws uncaught exception [object object] line no: unknown and white screen in simulator. In firefox browser 36, it runs fine without reporting any error in firebug.

Somebody, please help!