Fix "Unknown error"

[rankynbass]

This is a fix for "Unknown Error" when the user does not have an active subscription.

OauthLoginException expects to get an error message in a particular format. XL.Core doesn't interact with that part of Launcher.cs, so in order to get the error message to display properly, we have to wrap it like this: window.external.user("login=auth,ng,err,Error Message");