Liquid error: Solution::ArticleMeta#visible? delegated to solution_folder_meta.visible?, but solution_folder_meta is nil: #<Solution::ArticleMeta id: 15000018473, position: nil, art_type: 1, thumbs_up: 0, thumbs_down: 0, hits: 0, solution_folder_meta_id: 15000014175, account_id: 851581, created_at: "2018-12-03 09:40:59.000000000 +0100", updated_at: nil, available: nil, draft_present: nil, published: nil, outdated: nil>