fix Display groups

lib/src/screens/display/display.dart

@@ -95,8 +95,9 @@ class DisplayScreenLoaded extends HookConsumerWidget {
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    final fights = useState(
-        eventData.fights.where((element) => element.group == group).toList());
+    final fights = useState(eventData.fights
+        .where((element) => group == null || element.group == group)
+        .toList());
     final nextFight = useMemoized(() {
       Future.delayed(const Duration(seconds: 30), () async {
         fights.value = (await (await ref.read(eventRepositoryProvider.future))