Fatal error: Uncaught TypeError: Argument 1 passed to Sokil\IsoCodes\Database\Countries::getByAlpha2() must be of the type string, null given, called in /var/www/www.nureinvestigacion.es/httpdocs/OJS/pages/search/SearchHandler.inc.php on line 272 and defined in /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/lib/vendor/sokil/php-isocodes/src/Database/Countries.php:42
Stack trace:
#0 /var/www/www.nureinvestigacion.es/httpdocs/OJS/pages/search/SearchHandler.inc.php(272): Sokil\IsoCodes\Database\Countries->getByAlpha2()
#1 /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/classes/core/PKPRouter.inc.php(391): SearchHandler->authors()
#2 /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/classes/core/PKPPageRouter.inc.php(231): PKPRouter->_authorizeInitializeAndCallRequest()
#3 /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/classes/core/Dispatcher.inc.php(143): PKPPageRouter->route()
#4 /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/classes/core/PKPApplication.inc.php(281): Dispatcher->dispatch( in /var/www/www.nureinvestigacion.es/httpdocs/OJS/lib/pkp/lib/vendor/sokil/php-isocodes/src/Database/Countries.php on line 42