Fixed missing stack when exception is thrown

[arsu-leo]

When testing for stack on errors, the statements were reversed. For instance, if user code throws an exception, it states "No Error Stack Available" on the error making it quite difficult to debug. Furthermore, if client browser's Errors would not have the stack field, the fixed statements would throw an exception.

[arsu-leo]

I was trying to properly submit a change but I'm being rejected due someone's mail not being valid.

Someone who has nothing to to with my commit/pull request.

I will leave this here and is up to you to take care of your messy process.