Fatal error: Uncaught Functional\Exceptions\InvalidArgumentException: Functional\flatten() expects parameter 1 to be array or instance of Traversable, integer given in /data/web/e65198/html/jtl-shop/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php:272 Stack trace: #0 /data/web/e65198/html/jtl-shop/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php(70): Functional\Exceptions\InvalidArgumentException::assertCollectionAlike() #1 /data/web/e65198/html/jtl-shop/includes/vendor/lstrojny/functional-php/src/Functional/Flatten.php(26): Functional\Exceptions\InvalidArgumentException::assertCollection() #2 /data/web/e65198/html/jtl-shop/includes/src/News/Category.php(300): Functional\flatten() #3 /data/web/e65198/html/jtl-shop/includes/src/News/Controller.php(214): JTL\News\Category->getOverview() #4 /data/web/e65198/html/jtl-shop/news.php(81): JTL\News\Controller->displayOverview() #5 /data/web/e65198/html/jtl-shop/index.php(13): require('/data/web/e6519...') #6 {main} thrown in /data/web/e65198/html/jtl-shop/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php on line 272