Weak callback not called for an uncaught exception.

[Jane Chen]

I create an Error object registered with weak callback and throw it from my function callback.  If the script has try catch and catches the error, my weak callback is called during GC.  If the script does not catch it, but instead my TryCatch running the script  catches it, my weak callback does not seem to ever be called. 

Has anyone else seen this behavior?  Is this a bug?