My query_factory.php file has no such code as posted in the fix

private $link; // mysqli object

see below

/**
* Queryfactory - A simple database abstraction layer
*
*/
class queryFactory extends base {
var $link, $count_queries, $total_query_time, $dieOnErrors;
var $error_number = 0;
var $error_text = '';

function __construct() {
$this->count_queries = 0;
$this->total_query_time = 0;
}