'process is not defined' in callbacks mode on browser

[andrewdep]

You get this error from Streamline on the client (browser) in the case where it is trying to pass an error to a callback and the callback itself throws an exception:
'ReferenceError: process is not defined'
This is due to this line: https://github.com/Sage/streamlinejs/blob/master/lib/callbacks/runtime.js#L140
Of course, process is not defined in the browser. It is a nodejs global.