Is it possible that you changed your email address from a different machine/browser but you were still logged in on another machine or browser (perhaps with a persistent cookie)? Then it might cause an error because your cookie says you are authenticated and in allowed edit roles but when it tries to get a SiteUser object it comes back null because your cookie doe snot match the updated user.
The solution is to sign out and then sign in again so that your authentication cookie matches your user.
Hope that helps,
Joe