fetchCowGroups method Null safety

Implementation

Future<List<CowGroup>> fetchCowGroups() async {
  LogManager().addLog("fetchCowGroups", screen: runtimeType.toString());
  try {
    List<dynamic> body = await reqGET(path: '/api/cow_groups', queryParameters: {
      "farm_id": farmState.currentFarm!.id,
    });
    final List<CowGroup> cowGroups = body.map((element) => CowGroup.fromJson(element)).toList();
    cowGroupState.cowGroups = cowGroups;
    return cowGroups;
  } catch (e) {
    LogManager().addLog("fetchCowGroups call failed: $e", screen: runtimeType.toString());
    return [];
  }
}