title: Angularfire2: logout exception & best practices
body: <p>After logging in, I subscribe to some firebase refs, and then subsequently logout (FirebaseAuth.logout). Once I logout, I get a Firebase warning in the console: "Exception was thrown by user callback. Error: permission_denied at ...." and this becomes an actual exception. While I do expect to see this behavior, what are the best practices for logging a user out so I don't see this warning/exception? </p>