Fatal error: Uncaught TypeError: Argument 1 passed to Sokil\IsoCodes\Database\Countries::getByAlpha2() must be of the type string, null given, called in E:\inetpub\geofocus_ojs\pages\search\SearchHandler.inc.php on line 272 and defined in E:\inetpub\geofocus_ojs\lib\pkp\lib\vendor\sokil\php-isocodes\src\Database\Countries.php:42 Stack trace: #0 E:\inetpub\geofocus_ojs\pages\search\SearchHandler.inc.php(272): Sokil\IsoCodes\Database\Countries->getByAlpha2() #1 E:\inetpub\geofocus_ojs\lib\pkp\classes\core\PKPRouter.inc.php(391): SearchHandler->authors() #2 E:\inetpub\geofocus_ojs\lib\pkp\classes\core\PKPPageRouter.inc.php(231): PKPRouter->_authorizeInitializeAndCallRequest() #3 E:\inetpub\geofocus_ojs\lib\pkp\classes\core\Dispatcher.inc.php(143): PKPPageRouter->route() #4 E:\inetpub\geofocus_ojs\lib\pkp\classes\core\PKPApplication.inc.php(281): Dispatcher->dispatch() #5 E:\inetpub\geofocus_ojs\index.php(68): PKPApplication->execute() #6 {main} thrown in E:\inetpub\geofocus_ojs\lib\pkp\lib\vendor\sokil\php-isocodes\src\Database\Countries.php on line 42