flutter _TypeError (type '_InternalLinkedHashMap<dynamic, dynamic>' is not a subtype of type 'String' code example

Example: type '_InternalLinkedHashMap' is not a subtype of type 'Map'

Future>> fetch() async {
  http.Response response = await http.get('http://10.0.2.2:8000/api/membres');
  if (response.statusCode != 200) return null;
  return List>.from(json.decode(response.body)['membre']);
}