I don’t know what Scrumptious’s issue is, but I just fixed mine.
The problem was with my bad handling of applicationOpen in a system event listener. This event is generated when doing a Facebook login.
IMPORTANT NOTE: If you have a runtime error in a system event listener, Facebook can fail on facebook.login(), and you can get a Facebook event of phase “loginFailed” with no error content and no detail in your log for what the runtime error was.
Here’s the link to the doc that shows how to see the detail of an unhandled runtime error. Adding this listener showed me the error that was occurring in my system event listener.
http://www.coronalabs.com/blog/2013/03/06/run-time-error-handling/