JavaScriptCore: exception/error handling is missing necessary stuff

[ewmailing]

When an error occurs in the SWIG wrapper functions, it creates a string which is used as the exception. This is insufficient for being able to get the file name and line number to track down the error in your JavaScript code.

Additionally, JSCore expects an actual JSValueRef to be returned and not NULL, even on the error case.

In my JSBugs2 branch at https://github.com/ewmailing/swig, I have fixes for this.

The commit logs contain a lot more information. I will submit a pull request shortly.

ewmailing/swig@be938aa
ewmailing/swig@8b3bd4f