null safety

lib/pages/shipment/shipment_pack.dart

@@ -11,14 +11,14 @@ import 'package:fcs/pages/widgets/local_title.dart';
 import 'package:fcs/pages/widgets/progress.dart';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
-import 'package:flutter_icons/flutter_icons.dart';
+import 'package:flutter_icons_null_safety/flutter_icons_null_safety.dart';
 import 'package:intl/intl.dart';
 import 'package:provider/provider.dart';
 
 import 'widgets.dart';
 
 class ShipmentPack extends StatefulWidget {
-  final Shipment shipment;
+  final Shipment? shipment;
   ShipmentPack({this.shipment});
 
   @override
@@ -29,12 +29,12 @@ class _ShipmentPackState extends State<ShipmentPack> {
   var dateFormatter = new DateFormat('dd MMM yyyy');
   var timeFormatter = new DateFormat('jm');
 
-  Shipment _shipment;
+  Shipment? _shipment;
   bool _isLoading = false;
   var now = new DateTime.now();
 
-  FcsShipment _fcsShipment;
-  List<FcsShipment> _fcsShipments;
+  FcsShipment? _fcsShipment;
+  List<FcsShipment>? _fcsShipments;
 
   @override
   void initState() {
@@ -48,8 +48,8 @@ class _ShipmentPackState extends State<ShipmentPack> {
     FcsShipmentModel fcsShipmentModel =
         Provider.of<FcsShipmentModel>(context, listen: false);
     var fcsShipments = await fcsShipmentModel.getActiveFcsShipments();
-    var fcsShipment = fcsShipments
-        .firstWhere((e) => e.id == _shipment.fcsShipmentID, orElse: () => null);
+    var fcsShipment =
+        fcsShipments.firstWhere((e) => e.id == _shipment?.fcsShipmentID);
     setState(() {
       _fcsShipments = fcsShipments;
       _fcsShipment = fcsShipment;
@@ -58,7 +58,7 @@ class _ShipmentPackState extends State<ShipmentPack> {
 
   @override
   Widget build(BuildContext context) {
-    final shipmentNumberBox = getShipmentNumberStatus(context, _shipment);
+    final shipmentNumberBox = getShipmentNumberStatus(context, _shipment!);
 
     var fcsShipmentsBox = LocalDropdown<FcsShipment>(
       callback: (v) {
@@ -120,14 +120,14 @@ class _ShipmentPackState extends State<ShipmentPack> {
   }
 
   _save() async {
-    _shipment.fcsShipmentID = this._fcsShipment.id;
+    _shipment!.fcsShipmentID = this._fcsShipment!.id;
     setState(() {
       _isLoading = true;
     });
     try {
       ShipmentModel shipmentModel =
           Provider.of<ShipmentModel>(context, listen: false);
-      await shipmentModel.packShipment(_shipment);
+      await shipmentModel.packShipment(_shipment!);
       Navigator.pop(context, true);
     } catch (e) {
       showMsgDialog(context, "Error", e.toString());