build_runner watch can not run

[hxse]

Describe the bug

PS D:\Note\02-Computer\program\flutter\flutter_desktop_demo> flutter pub  run build_runner watch
Failed to build build_runner:build_runner:
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

 - package:build_runner_core
 - package:io
 - package:build_runner
 - package:build
 - package:build_config
 - package:build_daemon
 - package:build_resolvers
 - package:timing
 - package:graphs
 - package:package_config
 - package:code_builder
 - package:dart_style
 - package:http_multi_server
 - package:pubspec_parse
 - package:analyzer
 - package:checked_yaml
 - package:shelf_web_socket
 - package:web_socket_channel
 - package:_fe_analyzer_shared

For solutions, see https://dart.dev/go/unsound-null-safety
/C:/Users/hxse/scoop/apps/flutter/current/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.5/bin/build_runner.dart:91:37: Error: Operator '[]' cannot be called on 'ArgResults?' because it is potentially null.    
 - 'ArgResults' is from 'package:args/src/arg_results.dart' ('/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/args-2.3.0/lib/src/arg_results.dart').
    var verbose = parsedArgs.command['verbose'] as bool ?? false;       
                                    ^
/C:/Users/hxse/scoop/apps/flutter/current/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.5/bin/build_runner.dart:91:49: Warning: Operand of null-aware operation '??' has type 'bool' which excludes null.        
    var verbose = parsedArgs.command['verbose'] as bool ?? false;       
                                                ^
/C:/Users/hxse/scoop/apps/flutter/current/.pub-cache/hosted/pub.dartlang.org/build_runner-1.11.5/bin/build_runner.dart:101:9: Warning: Operand of null-aware operation '?.' has type 'StreamSubscription<dynamic>' which excludes null.
 - 'StreamSubscription' is from 'dart:async'.
  await logListener?.cancel();
        ^
/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/analyzer-0.41.2/lib/src/error/best_practices_verifier.dart:258:50: Error: The property 'displayString' is defined in multiple extensions for 
'TargetKind' and neither is more specific.
 - 'TargetKind' is from 'package:meta/meta_meta.dart' ('/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/meta-1.7.0/lib/meta_meta.dart').
Try using an explicit extension application of the wanted extension or hiding unwanted extensions from scope.
        var kindNames = kinds.map((kind) => kind.displayString).toList()                                                 ^^^^^^^^^^^^^
/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/analyzer-0.41.2/lib/src/error/best_practices_verifier.dart:1950:14: Context: This is one of the extension members.
  String get displayString {
             ^^^^^^^^^^^^^
/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/meta-1.7.0/lib/meta_meta.dart:91:14: Context: This is one of the extension members.
  String get displayString {
             ^^^^^^^^^^^^^
/C:/Users/hxse/scoop/apps/flutter/2.8.1/.pub-cache/hosted/pub.dartlang.org/analyzer-0.41.2/lib/src/error/best_practices_verifier.dart:260:36: Error: The getter 'commaSeparatedWithOr' isn't defined for the class 'List<dynamic>'.
 - 'List' is from 'dart:core'.
Try correcting the name to the name of an existing getter, or defining a getter or field named 'commaSeparatedWithOr'.
        var validKinds = kindNames.commaSeparatedWithOr;
                                   ^^^^^^^^^^^^^^^^^^^^
pub finished with exit code 1

To Reproduce

1. flutter create .
2. add following code in main.dart
3. flutter pub run build_runner watch

import 'package:flutter/foundation.dart';
import 'package:functional_widget_annotation/functional_widget_annotation.dart';
import 'package:flutter/widgets.dart';

part 'main.g.dart';

// we create a widget using a widget decorated by `@swidget`
@swidget
Widget foo(int value) {
  return Container();
}

@swidget
Widget example(
  int foo,
  String bar, {
  ValueChanged<bool>? onChanged,
}) {
  return Container();
}

void main() => runApp(
      // we use the generated class
      const Foo(42),
    );

my pubspec.yaml

name: flutter_desktop_demo
description: A new Flutter project.

publish_to: 'none' # Remove this line if you wish to publish to pub.dev
https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.15.1 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  functional_widget_annotation: ^0.8.0
  flutter_hooks : any

  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter
  functional_widget: ^0.8.0
  build_runner: ^1.9.0

  flutter_lints: ^1.0.0

# The following section is specific to Flutter.
flutter:

  uses-material-design: true

Expected behavior
I just run the example code, I hope to run normally.

[hxse]

flutter pub outdated --mode=null-safety
According to command(null-safety) upgrade package solves the problem