Warning: Undefined property: stdClass::$author in /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php on line 998

Fatal error: Uncaught TypeError: array_udiff(): Argument #2 must be of type array, null given in /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php:998 Stack trace: #0 /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php(998): array_udiff() #1 /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php(487): APP\plugins\generic\citationStyleLanguage\CitationStyleLanguagePlugin->setBookChapterAuthors() #2 /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php(341): APP\plugins\generic\citationStyleLanguage\CitationStyleLanguagePlugin->getCitation() #3 [internal function]: APP\plugins\generic\citationStyleLanguage\CitationStyleLanguagePlugin->getTemplateData() #4 /var/www/omp/uptc_34/omp/lib/pkp/classes/plugins/Hook.php(139): call_user_func_array() #5 /var/www/omp/uptc_34/omp/lib/pkp/classes/plugins/Hook.php(113): PKP\plugins\Hook::run() #6 /var/www/omp/uptc_34/omp/pages/catalog/CatalogBookHandler.php(302): PKP\plugins\Hook::call() #7 [internal function]: APP\pages\catalog\CatalogBookHandler->book() #8 /var/www/omp/uptc_34/omp/lib/pkp/classes/core/PKPRouter.php(334): call_user_func() #9 /var/www/omp/uptc_34/omp/lib/pkp/classes/core/PKPPageRouter.php(278): PKP\core\PKPRouter->_authorizeInitializeAndCallRequest() #10 /var/www/omp/uptc_34/omp/lib/pkp/classes/core/Dispatcher.php(165): PKP\core\PKPPageRouter->route() #11 /var/www/omp/uptc_34/omp/lib/pkp/classes/core/PKPApplication.php(395): PKP\core\Dispatcher->dispatch() #12 /var/www/omp/uptc_34/omp/index.php(21): PKP\core\PKPApplication->execute() #13 {main} thrown in /var/www/omp/uptc_34/omp/plugins/generic/citationStyleLanguage/CitationStyleLanguagePlugin.php on line 998