Fatal error: Uncaught Functional\Exceptions\InvalidArgumentException: Functional\flatten() expects parameter 1 to be array or instance of Traversable, integer given in /usr/www/users/jagdak/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php:271 Stack trace: #0 /usr/www/users/jagdak/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php(69): Functional\Exceptions\InvalidArgumentException::assertCollectionAlike() #1 /usr/www/users/jagdak/includes/vendor/lstrojny/functional-php/src/Functional/Flatten.php(25): Functional\Exceptions\InvalidArgumentException::assertCollection() #2 /usr/www/users/jagdak/includes/src/News/Category.php(300): Functional\flatten() #3 /usr/www/users/jagdak/includes/src/News/Controller.php(214): JTL\News\Category->getOverview() #4 /usr/www/users/jagdak/news.php(81): JTL\News\Controller->displayOverview() #5 /usr/www/users/jagdak/index.php(13): require('/usr/www/users/...') #6 {main} thrown in /usr/www/users/jagdak/includes/vendor/lstrojny/functional-php/src/Functional/Exceptions/InvalidArgumentException.php on line 271