throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
} elseif ($this->ifUserGuestIsTaken($userName) === false) {
// Username is already taken
throw new FilterChainException($this, self::EXCEPTION_FILTER_CHAIN_INTERCEPTED);
} elseif ($this->ifUserGuestIsTaken($userName) === false) {
// Username is already taken