Let's say I'm logged in and I want to delete my own user record. If I call the logout() after the record was deleted, it fails here (AuthenticationBase.php line 188):
$this->loginModel->purgeRememberTokens($user->id);
because $user is NULL.
However, if I would call the logout before deleting the record, it is possible that the delete process fails (for whatever reason) and I was logged out unnecessarily.
It would be nice to use the logout without 500 error when the user doesn't exist or not logged in - just to clean up the cookies.