Fatal error: Uncaught Error: Call to a member function query() on null in C:xampphtdocsa.commodulesmysql_PDO.php:44 Stack trace: #0 C:xampphtdocsa.comcontrolslist.php(20): mysql_PDO->query('SELECT * FROM s...', false) #1 C:xampphtdocsa.comindex.php(140): list_control->start() #2 {main} thrown in C:xampphtdocsa.commodulesmysql_PDO.php on line 44

class list_control
{

    private $lang;

    function __construct($lang)
    {
        $this->lang = $lang;
        loadModule('mysql_PDO');
    }

    public function start() {

        global $dbc;

        $db = new mysql_PDO($dbc['host'], $dbc['user'], $dbc['password'], $dbc['dbase']);
        $db->connect();
        $db->query('SELECT * FROM slug', false);

        load('list', $this->lang);

        $db = null;

    }

}

class mysql_PDO
    {


        private $host;
        private $user;
        private $password;
        private $dbase;
        private $char;
        public $db;


        function __construct($host, $user, $password, $dbase, $char = 'UTF8mb4')
        {
            $this->host = $host;
            $this->user = $user;
            $this->password = $password;
            $this->dbase = $dbase;
            $this->char = $char;

            function clearStr($str) {

                $str = htmlspecialchars(trim(mysqli_real_escape_string($str)));
                return $str;

            }


        }

        public function connect() {

            $db = new PDO('mysql:host='.$this->host.';dbname='.$this->dbase.'', $this->user, $this->password) or die();
            $db->exec('SET NAMES '.$this->char.'');

        }

        public function query($query, $bool = false) {

            $result = $this->db->query($query); //ВОТ 44 СТРОКА
            $result->execute();

            if ($bool == false) {
                $return = $result->fetchAll();
                return $return;
            } else {
                return $result;
            }

        }

        public function close() {

            $this->db = null;

        }

    }