public function first($key)
    {
        if ($this->has($key)) {
            $err = $this->_errors[$key];
            if (is_array($err)) {
                for ($i = 0; $i < count($err); $i++) {
                    if (!empty($err[$i])) {
                        return $err[$i];
                    }
                }
            } else {
                return $err;
            }
        }

        return ''; // return empty string since no key found to prevent errors
    }