`TraceKit.computeStackTrace` evaluates error to `{}`

[Myztiq]

I have created a reproduction hosted here: http://raven-undefined.divshot.io/
With source here: https://github.com/Myztiq/raven-undefined

A request to an invalid file triggers an error with the message Unexpected token < and when TraceKit.computeStackTrace is done it results in {} being spat out. When used in conjunction with Raven this results in sentry getting errors with undefined as the value and message.

[niemyjski]

@Myztiq , I'm helping manage the TraceKit project. Can you please create a pull request for this here https://github.com/csnover/TraceKit so we can get it merged in.