我使用Dio来获取响应，这是我的建模类：

import 'package:shoppingcenter/screens/homePage.dart';

class MALL {
  late final int id;
  late final String name;
  late final String images;

  MALL({required this.id, required this.name, required this.images});

  factory MALL.fromJson(Map<String, dynamic> data) {
    final id = data['id'];
    final name = data['name'];
    final images = data['images'];
    return MALL(id: id, name: name, images: images);
  }
}

class City {
  final List<MALL> malls;

  City({required this.malls});

  factory City.fromJson(Map<String, dynamic> data) {
    final mallData = data['malls'] as List<dynamic>?;
    final malls = mallData != null ? mallData.map((mallData) => MALL.fromJson(mallData)).toList() : <MALL>[];
    return City(malls: malls);
  }
}

当我尝试使用我的类时，我得到这个错误：

Error: Expected a value of type 'Map<String, dynamic>', but got one of type 'String'

我的JSON是：

{
  "malls": [
    {
      "id": 1,
      "name": "city center",
      "images": "city.jpg"
    }
  ]
}

我的响应代码：

Future<List<MALL>> get() async {
  final dio = Dio();
  var url = 'My URL';
  Response response = await dio.get(url);
  City api = City.fromJson(response.data);
  return api.malls;
}

我该怎么办？