this code give me error 500

please, guys, this code give me error 500 but when i remove this -> result_array() its worked but I don't know when problem

function getCodeForCity($destination
        {
          $result = $this->db->query("SELECT code FROM hotels WHERE MATCH (city_slug) AGAINST ('$destination' IN BOOLEAN MODE)")->result_array();
          return $result;
        }