check null safety

lib/pages/widgets/banner.dart

@@ -3,7 +3,7 @@ import 'package:flutter/material.dart';
 
 class FlavorBanner extends StatelessWidget {
   final Widget child;
-  FlavorBanner({@required this.child});
+  FlavorBanner({required this.child});
 
   @override
   Widget build(BuildContext context) {

lib/pages/widgets/barcode_scanner.dart

@@ -1,9 +1,9 @@
-import 'package:barcode_scan/barcode_scan.dart';
+import 'package:barcode_scan2/platform_wrapper.dart';
 
-Future<String> scanBarcode() async {
+Future<String?> scanBarcode() async {
   try {
-    String barcode = await BarcodeScanner.scan();
-    if (barcode == null) return null;
+    var scanResult = await BarcodeScanner.scan();
+    String barcode = scanResult.rawContent;
 
     String gs = String.fromCharCode(29);
     if (barcode.contains(gs)) {

lib/pages/widgets/bottom_widgets.dart

@@ -13,7 +13,7 @@ class BottomWidgets extends StatelessWidget {
   Widget build(BuildContext context) {
     var pkgInfo = Provider.of<MainModel>(context).packageInfo;
     final versionBox = Text(
-      "v${pkgInfo.version}+${pkgInfo.buildNumber}",
+      "v${pkgInfo?.version}+${pkgInfo?.buildNumber}",
       style: TextStyle(color: Colors.white30),
     );
     return Column(