Fatal error: Uncaught Error: Undefined constant "PKP\controllers\grid\PKP_STRICT_MODE" in C:\xampp\htdocs\ojs\lib\pkp\classes\controllers\grid\GridDataProvider.php:130 Stack trace: #0 {main} thrown in C:\xampp\htdocs\ojs\lib\pkp\classes\controllers\grid\GridDataProvider.php on line 130