Fatal error: Uncaught exception 'PropelException' with message 'filterByCategory() only accepts arguments of type Category or PropelCollection' in /www/application/models/build/classes/mkrzymowski/om/BaseArticleQuery.php:681 Stack trace: #0 /www/application/modules/main/Categories/CategoriesController.class.php(12): BaseArticleQuery->filterByCategory(NULL) #1 /www/application/core/VF_FrontController.class.php(269): CategoriesController->DisplayAction() #2 /www/index.php(31): VF_FrontController->dispatch() #3 {main} thrown in /www/application/models/build/classes/mkrzymowski/om/BaseArticleQuery.php on line 681