How to diagnose browser widget JS handlers failing silently?

[Keith Clarke]

Folks,
Is there any way to see the raw message that arrive in LC from javascripts in a browser widget?

I’m getting silent failures on some JSHandlers and would like to determine whether it’s JS failing to send (unlikely as they’re variations on working themes) or LC rejecting the inbound message due to syntax, unescaped quotes, etc.
Thanks
Keith