private $mysqli;

    function baseConnect()
    {
        $db_info = parse_ini_file("../conf/db.ini");
        $host = $db_info['host'];
        $user = $db_info['user'];
        $pass = $db_info['pass'];
        $base = $db_info['base'];
        $this->mysqli = new mysqli($host, $user, $pass, $base);
    }

$select = $this->mysqli->query($db);

Call to a member function query() on null

$this->mysqli =