我正在从事电子商务应用程序的项目。flutter对我来说是新的，所以请帮助我这是我从快速类型获得的模型。类型'Null'不是'Map'类型的子类型

OrderListModel orderListModelsFromJson(String str) => OrderListModel.fromJson(json.decode(str));

String orderListModelsToJson(OrderListModel data) => json.encode(data.toJson());

class OrderListModel {
  OrderListModel({
    this.error,
    this.errorMessage,
    this.content,
  });

  bool? error;
  String? errorMessage;
  Content? content;

  factory OrderListModel.fromJson(Map<String, dynamic> json) => OrderListModel(
    error: json["error"],
    errorMessage: json["errorMessage"],
    content: Content.fromJson(json["content"]),
  );

  Map<String, dynamic> toJson() => {
    "error": error,
    "errorMessage": errorMessage,
    "content": content!.toJson(),
  };
}

class Content {
  Content({
    this.currentPage,
    this.data,
    this.firstPageUrl,
    this.from,
    this.lastPage,
    this.lastPageUrl,
    this.nextPageUrl,
    this.path,
    this.perPage,
    this.prevPageUrl,
    this.to,
    this.total,
  });

  int? currentPage;
  List<Order>? data;
  String? firstPageUrl;
  int? from;
  int? lastPage;
  String? lastPageUrl;
  String? nextPageUrl;
  String? path;
  String? perPage;
  dynamic? prevPageUrl;
  int? to;
  int? total;

  factory Content.fromJson(Map<String, dynamic> json) => Content(
    currentPage: json["current_page"],
    data: List<Order>.from(json["data"].map((x) => Order.fromJson(x))),
    firstPageUrl: json["first_page_url"],
    from: json["from"],
    lastPage: json["last_page"],
    lastPageUrl: json["last_page_url"],
    nextPageUrl: json["next_page_url"],
    path: json["path"],
    perPage: json["per_page"],
    prevPageUrl: json["prev_page_url"],
    to: json["to"],
    total: json["total"],
  );

  Map<String, dynamic> toJson() => {
    "current_page": currentPage,
    "data": List<dynamic>.from(data!.map((x) => x.toJson())),
    "first_page_url": firstPageUrl,
    "from": from,
    "last_page": lastPage,
    "last_page_url": lastPageUrl,
    "next_page_url": nextPageUrl,
    "path": path,
    "per_page": perPage,
    "prev_page_url": prevPageUrl,
    "to": to,
    "total": total,
  };
}

class Order {
  Order({
    this.orderId,
    this.shopId,
    this.shop,
    this.deliveryType,
    this.netTotalAmount,
    this.deliveryAddressId,
    this.totalDiscount,
    this.coupon,
    this.scheduleTime,
    this.orderReferenceId,
    this.status,
    this.orderPlaceTime,
    this.deliveredTime,
    this.deliveryStaffId,
    this.updatedAt,
    this.cartId,
    this.adminServiceCharge,
    this.shopEarning,
    this.orderSuggestions,
    this.deliverycharge,
    this.partiallyComplete,
    this.markReady,
    this.partiallyCompleteReason,
    this.productTotalAmount,
    this.deliveryId,
    this.tax,
    this.taxAmount,
    this.couponPercentage,
    this.user,
    this.address,
  });

  int? orderId;
  int? shopId;
  Shop? shop;
  int? deliveryType;
  double? netTotalAmount;
  int? deliveryAddressId;
  double? totalDiscount;
  Coupon? coupon;
  String? scheduleTime;
  String? orderReferenceId;
  Status? status;
  DateTime? orderPlaceTime;
  DateTime? deliveredTime;
  int? deliveryStaffId;
  List<dynamic>? updatedAt;
  int? cartId;
  String? adminServiceCharge;
  String? shopEarning;
  dynamic? orderSuggestions;
  dynamic? deliverycharge;
  int? partiallyComplete;
  String? markReady;
  dynamic? partiallyCompleteReason;
  dynamic? productTotalAmount;
  int? deliveryId;
  int? tax;
  int? taxAmount;
  String? couponPercentage;
  User? user;
  dynamic? address;

  factory Order.fromJson(Map<String, dynamic> json) => Order(
    orderId: json["orderId"],
    shopId: json["shopId"],
    shop: Shop.fromJson(json["shop"]),
    deliveryType: json["deliveryType"],
    netTotalAmount: json["netTotalAmount"].toDouble(),
    deliveryAddressId: json["deliveryAddressId"],
    totalDiscount: json["totalDiscount"].toDouble(),
    coupon: Coupon.fromJson(json["coupon"]),
    scheduleTime: json["scheduleTime"],
    orderReferenceId: json["orderReferenceId"],
    status: Status.fromJson(json["status"]),
    orderPlaceTime: DateTime.parse(json["orderPlaceTime"]),
    deliveredTime: DateTime.parse(json["deliveredTime"]),
    deliveryStaffId: json["deliveryStaffId"],
    updatedAt: List<dynamic>.from(json["updated_at"].map((x) => x)),
    cartId: json["cartId"],
    adminServiceCharge: json["adminServiceCharge"],
    shopEarning: json["shopEarning"],
    orderSuggestions: json["orderSuggestions"],
    deliverycharge: json["deliverycharge"],
    partiallyComplete: json["partiallyComplete"],
    markReady: json["markReady"],
    partiallyCompleteReason: json["partiallyCompleteReason"],
    productTotalAmount: json["productTotalAmount"],
    deliveryId: json["deliveryId"],
    tax: json["tax"],
    taxAmount: json["taxAmount"],
    couponPercentage: json["couponPercentage"],
    user: User.fromJson(json["User"]),
    address: json["Address"],
  );

  Map<String, dynamic> toJson() => {
    "orderId": orderId,
    "shopId": shopId,
    "shop": shop!.toJson(),
    "deliveryType": deliveryType,
    "netTotalAmount": netTotalAmount,
    "deliveryAddressId": deliveryAddressId,
    "totalDiscount": totalDiscount,
    "coupon": coupon!.toJson(),
    "scheduleTime": scheduleTime,
    "orderReferenceId": orderReferenceId,
    "status": status!.toJson(),
    "orderPlaceTime": orderPlaceTime!.toIso8601String(),
    "deliveredTime": deliveredTime!.toIso8601String(),
    "deliveryStaffId": deliveryStaffId,
    "updated_at": List<dynamic>.from(updatedAt!.map((x) => x)),
    "cartId": cartId,
    "adminServiceCharge": adminServiceCharge,
    "shopEarning": shopEarning,
    "orderSuggestions": orderSuggestions,
    "deliverycharge": deliverycharge,
    "partiallyComplete": partiallyComplete,
    "markReady": markReady,
    "partiallyCompleteReason": partiallyCompleteReason,
    "productTotalAmount": productTotalAmount,
    "deliveryId": deliveryId,
    "tax": tax,
    "taxAmount": taxAmount,
    "couponPercentage": couponPercentage,
    "User": user!.toJson(),
    "Address": address,
  };
}

class Coupon {
  Coupon({
    this.id,
    this.couponName,
    this.couponCode,
    this.discountPerscentage,
    this.maxDiscount,
    this.dateStart,
    this.dateEnd,
    this.status,
    this.couponImage,
    this.createdAt,
    this.updatedAt,
    this.outletId,
    this.isblock,
    this.isDeleted,
    this.numberOfUses,
    this.isAdminCoupon,
  });

  int? id;
  String? couponName;
  String? couponCode;
  int? discountPerscentage;
  int? maxDiscount;
  dynamic? dateStart;
  dynamic? dateEnd;
  int? status;
  dynamic? couponImage;
  DateTime? createdAt;
  DateTime? updatedAt;
  int? outletId;
  int? isblock;
  int? isDeleted;
  int? numberOfUses;
  int? isAdminCoupon;

  factory Coupon.fromJson(Map<String, dynamic> json) => Coupon(
    id: json["id"],
    couponName: json["couponName"],
    couponCode: json["couponCode"],
    discountPerscentage: json["discountPerscentage"],
    maxDiscount: json["maxDiscount"],
    dateStart: json["dateStart"],
    dateEnd: json["dateEnd"],
    status: json["status"],
    couponImage: json["couponImage"],
    createdAt: DateTime.parse(json["created_at"]),
    updatedAt: DateTime.parse(json["updated_at"]),
    outletId: json["outletId"],
    isblock: json["isblock"],
    isDeleted: json["isDeleted"],
    numberOfUses: json["numberOfUses"],
    isAdminCoupon: json["isAdminCoupon"],
  );

  Map<String, dynamic> toJson() => {
    "id": id,
    "couponName": couponName,
    "couponCode": couponCode,
    "discountPerscentage": discountPerscentage,
    "maxDiscount": maxDiscount,
    "dateStart": dateStart,
    "dateEnd": dateEnd,
    "status": status,
    "couponImage": couponImage,
    "created_at": createdAt!.toIso8601String(),
    "updated_at": updatedAt!.toIso8601String(),
    "outletId": outletId,
    "isblock": isblock,
    "isDeleted": isDeleted,
    "numberOfUses": numberOfUses,
    "isAdminCoupon": isAdminCoupon,
  };
}

class Shop {
  Shop({
    this.id,
    this.name,
    this.email,
    this.image,
    this.contactNumber,
    this.address,
  });

  int? id;
  String? name;
  String? email;
  String? image;
  String? contactNumber;
  Address? address;

这个下面的地址我得到了错误。

  factory Shop.fromJson(Map<String, dynamic> json) => Shop(
    id: json["id"],
    name: json["name"],
    email: json["email"],
    image: json["image"],
    contactNumber: json["contactNumber"],
    address: Address.fromJson(json["Address"]),
  );

  Map<String, dynamic> toJson() => {
    "id": id,
    "name": name,
    "email": email,
    "image": image,
    "contactNumber": contactNumber,
    "Address": address!.toJson(),
  };
}

I/flutter（21615）： type'Null'不是'Map'类型的子类型

class Address {
  Address({
    this.id,
    this.userId,
    this.location,
    this.houseFlatNo,
    this.fullAddress,
    this.type,
    this.unSaved,
    this.latitude,
    this.longitude,
    this.isDeleted,
    this.currentAddress,
    this.streetNo,
    this.streetName,
    this.country,
    this.zipcode,
    this.city,
  });

  int? id;
  int? userId;
  String? location;
  String? houseFlatNo;
  String? fullAddress;
  dynamic? type;
  int? unSaved;
  double? latitude;
  double? longitude;
  int? isDeleted;
  int? currentAddress;
  String? streetNo;
  String? streetName;
  String? country;
  int? zipcode;
  String? city;

  factory Address.fromJson(Map<String, dynamic> json) => Address(
    id: json["id"],
    userId: json["userId"],
    location: json["location"],
    houseFlatNo: json["houseFlatNo"],
    fullAddress: json["fullAddress"],
    type: json["type"],
    unSaved: json["unSaved"],
    latitude: json["latitude"].toDouble(),
    longitude: json["longitude"].toDouble(),
    isDeleted: json["isDeleted"],
    currentAddress: json["currentAddress"],
    streetNo: json["streetNo"],
    streetName: json["streetName"],
    country: json["country"],
    zipcode: json["zipcode"],
    city: json["city"],
  );

  Map<String, dynamic> toJson() => {
    "id": id,
    "userId": userId,
    "location": location,
    "houseFlatNo": houseFlatNo,
    "fullAddress": fullAddress,
    "type": type,
    "unSaved": unSaved,
    "latitude": latitude,
    "longitude": longitude,
    "isDeleted": isDeleted,
    "currentAddress": currentAddress,
    "streetNo": streetNo,
    "streetName": streetName,
    "country": country,
    "zipcode": zipcode,
    "city": city,
  };
}

class Status {
  Status({
    this.id,
    this.name,
  });

  int? id;
  dynamic? name;

  factory Status.fromJson(Map<String, dynamic> json) => Status(
    id: json["id"],
    name: json["name"],
  );

  Map<String, dynamic> toJson() => {
    "id": id,
    "name": name,
  };
}

class User {
  User({
    this.id,
    this.firstName,
    this.lastName,
    this.email,
    this.mobileNumber,
    this.countryCode,
  });

  int? id;
  String? firstName;
  dynamic? lastName;
  String? email;
  String? mobileNumber;
  String? countryCode;

  factory User.fromJson(Map<String, dynamic> json) => User(
    id: json["id"],
    firstName: json["firstName"],
    lastName: json["lastName"],
    email: json["email"],
    mobileNumber: json["mobileNumber"],
    countryCode: json["countryCode"],
  );

  Map<String, dynamic> toJson() => {
    "id": id,
    "firstName": firstName,
    "lastName": lastName,
    "email": email,
    "mobileNumber": mobileNumber,
    "countryCode": countryCode,
  };
}