protected function fetchResult(array $results, string $username): array
    {
        if (count($results) > 1) {
            throw new \Caridea\Auth\Exception\UsernameAmbiguous($username);
        } elseif (count($results) == 0) {
            throw new \Caridea\Auth\Exception\UsernameNotFound($username);
        }
        return current($results);
    }