Exception due to window already destroyed

[rogeru]

In my case I get 'will-navigate' and a 'did-get-redirect-request' which means onCallback is called a second time. Resolving a promise a second time does not harm, but the window is already close on the first callback and therefore an exception is raised when trying to access it or close it again.

Another minor issue is that opts.additionalTokenRequestData throws an exception if no options object is passed in.

I will create a pull request.

[aguynamedben]

Thanks for the PR, I'll review it soon and hopefully merge it (I'm new at helping maintain this repo, so it might take a little bit).