check null safety

lib/domain/entities/package.dart

@@ -5,35 +5,35 @@ import 'package:fcs/domain/vo/delivery_address.dart';
 import 'package:fcs/domain/vo/shipment_status.dart';
 
 class Package {
-  String id;
-  String trackingID;
-  String userID;
-  String fcsID;
-  String userName;
-  String phoneNumber;
-  DateTime currentStatusDate;
+  String? id;
+  String? trackingID;
+  String? userID;
+  String? fcsID;
+  String? userName;
+  String? phoneNumber;
+  DateTime? currentStatusDate;
   List<String> photoUrls;
   List<ShipmentStatus> shipmentHistory;
-  String desc;
+  String? desc;
 
-  String status;
-  String shipmentNumber;
-  String senderFCSID;
-  String senderName;
-  String senderPhoneNumber;
-  String boxNumber;
-  String cargoDesc;
-  String market;
+  String? status;
+  String? shipmentNumber;
+  String? senderFCSID;
+  String? senderName;
+  String? senderPhoneNumber;
+  String? boxNumber;
+  String? cargoDesc;
+  String? market;
   bool isChecked;
 
   int rate;
   int weight;
-  String packageType;
-  String pickUpID;
-  List<String> photos;
-  String remark;
-  DateTime arrivedDate;
-  DeliveryAddress deliveryAddress;
+  String? packageType;
+  String? pickUpID;
+  // List<String> photos;
+  String? remark;
+  DateTime? arrivedDate;
+  DeliveryAddress? deliveryAddress;
 
   //for packages in processing
   List<File> photoFiles;
@@ -42,35 +42,34 @@ class Package {
 
   double get price => rate.toDouble() * weight;
 
-  Package({
-    this.id,
-    this.trackingID,
-    this.userID,
-    this.userName,
-    this.fcsID,
-    this.phoneNumber,
-    this.shipmentNumber,
-    this.senderFCSID,
-    this.senderName,
-    this.boxNumber,
-    this.rate,
-    this.weight,
-    this.packageType,
-    this.pickUpID,
-    this.remark,
-    this.status,
-    this.arrivedDate,
-    this.cargoDesc,
-    this.market,
-    this.shipmentHistory,
-    this.currentStatusDate,
-    this.photoUrls,
-    this.desc,
-    this.deliveryAddress,
-    this.isChecked = false,
-    this.photoFiles,
-    this.senderPhoneNumber
-  });
+  Package(
+      {this.id,
+      this.trackingID,
+      this.userID,
+      this.userName,
+      this.fcsID,
+      this.phoneNumber,
+      this.shipmentNumber,
+      this.senderFCSID,
+      this.senderName,
+      this.boxNumber,
+      this.rate = 0,
+      this.weight = 0,
+      this.packageType,
+      this.pickUpID,
+      this.remark,
+      this.status,
+      this.arrivedDate,
+      this.cargoDesc,
+      this.market,
+      this.shipmentHistory = const [],
+      this.currentStatusDate,
+      this.photoUrls = const [],
+      this.desc,
+      this.deliveryAddress,
+      this.isChecked = false,
+      this.photoFiles = const [],
+      this.senderPhoneNumber});
 
   factory Package.fromMap(Map<String, dynamic> map, String docID) {
     var _currentStatusDate = (map['status_date'] as Timestamp);
@@ -98,9 +97,7 @@ class Package {
         senderName: map['sender_name'],
         senderPhoneNumber: map['sender_phone_number'],
         deliveryAddress: _da,
-        currentStatusDate: _currentStatusDate != null
-            ? _currentStatusDate.toDate().toLocal()
-            : null,
+        currentStatusDate: _currentStatusDate.toDate().toLocal(),
         photoUrls: _photoUrls,
         shipmentHistory: _shipmentStatus);
   }