Build failures on Flutter 3.44.4 / Proposal to update hooks and add a guard clause

[KomTak001]

Hi there, thank you for maintaining this excellent package!
I recently encountered build issues when using the latest version of Flutter. I would like to report the problem and propose a fix.

Environment

• velopack_flutter: 0.3.2
• Flutter: 3.44.4 / Dart: 3.12.x
• Platform: macOS (likely reproducible on Windows/Linux as well)

Problem

Running flutter run or flutter build on Flutter 3.44.4 causes a crash in the native assets build hook (hook/build.dart). This problem occurs in two stages, stemming from dependency versions and hook execution state.

1. Null check error during JSON parsing

Currently, velopack_flutter 0.3.2 depends on hooks ^1.0.3, which in turn resolves code_assets to 1.0.0. This version is incompatible with the newer native assets JSON format emitted by Flutter 3.44.4, resulting in the following error:

Unhandled exception:
Null check operator used on a null value
#0      new CodeConfig._fromJson (package:code_assets/src/code_assets/config.dart:52:67)
#1      HookConfigCodeConfig.code (package:code_assets/src/code_assets/config.dart:21:37)
#2      main.<anonymous closure> (velopack_flutter-0.3.2/hook/build.dart:7:35)

2. Bad state error when overriding to hooks ^2.0.0

To work around the first issue, I used dependency_overrides in my app's pubspec.yaml to force hooks: ^2.0.2. While this makes full builds (flutter build) succeed, incremental builds triggered by flutter run fail with a new error:

Bad state: HookConfig.code should only be accessed when building code assets.
Check HookConfig.buildCodeAssets before accessing HookConfig.code.

This happens because hook/build.dart unconditionally calls input.config.code.targetOS. With the newer hooks package, accessing this property throws an error if buildCodeAssets == false (which is the case for incremental builds).

Suggested Fix

To fully resolve this issue and eliminate the need for developers to use app-level dependency_overrides, would it be possible to apply the following two changes in a future release?

1. Update dependencies
Update the package dependencies to use hooks: ^2.0.0 (and consequently code_assets: ^1.2.0).

**2. Add a guard clause in hook/build.dart**
Add a check at the top of the file (before accessing input.config.code) to return early if code assets are not being built:

if (!input.config.buildCodeAssets) return;

I have verified locally that applying this dependency update along with the guard clause successfully allows both flutter build macos --debug and flutter run to complete without any errors.

Thank you for your time and assistance!

[GigaDroid]

Hi, this does not appear to be reproducible using the exact same setup (Flutter 3.44.4 on MacOS). Please provide more information about when exactly you are encountering this, are you trying to build the example app? Please try rebuilding from scratch, deleting any build caches which might exist.

[KomTak001]

@GigaDroid

Thanks for checking. This reproduces specifically with flutter run, not flutter build.

Flutter 3.44 changed hook invocation so flutter run does not request code assets
(PR flutter/flutter#181542). Hooks are still invoked with buildCodeAssets == false,
and velopack_flutter's hook/build.dart accesses input.config.code unconditionally.

Repro (example app is fine):

1. Flutter 3.44.4
2. flutter clean && flutter pub get
3. flutter run -d macos # fails
4. flutter build macos --debug # succeeds (no guard needed on this path)

With dependency_overrides: hooks: ^2.0.0, the failure becomes the documented
StateError about accessing HookConfig.code when buildCodeAssets is false —
same root cause, clearer message.

The fix is still the guard:
if (!input.config.buildCodeAssets) return;

When launching the sample app created with flutter create using flutter run -d macos, the following error occurs:

Unhandled exception:
Null check operator used on a null value
#0      new CodeConfig._fromJson (package:code_assets/src/code_assets/config.dart:52:67)
#1      HookConfigCodeConfig.code (package:code_assets/src/code_assets/config.dart:21:37)
#2      main.<anonymous closure> (file:///Users/user-name/.pub-cache/hosted/pub.dev/velopack_flutter-0.3.2/hook/build.dart:7:35)
#3      build (package:hooks/src/api/build_and_link.dart:191:18)
#4      main (file:///Users/user-name/.pub-cache/hosted/pub.dev/velopack_flutter-0.3.2/hook/build.dart:6:9)
#5      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:311:33)
#6      _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)


  Building assets for package:velopack_flutter failed.
  build.dart returned with exit code: 255.
  To reproduce run:
  (cd /Users/user-name/.pub-cache/hosted/pub.dev/velopack_flutter-0.3.2/; /Users/user-name/fvm/versions/3.44.4/bin/cache/dart-sdk/bin/dart
  --packages=/Users/user-name/work/tmp/for_check_flutter_sample_velopack/.dart_tool/package_config.json
  /Users/user-name/work/tmp/for_check_flutter_sample_velopack/.dart_tool/hooks_runner/velopack_flutter/337ce265dc/hook.dill
  --config=/Users/user-name/work/tmp/for_check_flutter_sample_velopack/.dart_tool/hooks_runner/velopack_flutter/337ce265dc/input.json )
  stderr:
  Unhandled exception:
Null check operator used on a null value
#0      new CodeConfig._fromJson (package:code_assets/src/code_assets/config.dart:52:67)
#1      HookConfigCodeConfig.code (package:code_assets/src/code_assets/config.dart:21:37)
#2      main.<anonymous closure> (file:///Users/user-name/.pub-cache/hosted/pub.dev/velopack_flutter-0.3.2/hook/build.dart:7:35)
#3      build (package:hooks/src/api/build_and_link.dart:191:18)
#4      main (file:///Users/user-name/.pub-cache/hosted/pub.dev/velopack_flutter-0.3.2/hook/build.dart:6:9)
#5      _delayEntrypointInvocation.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:311:33)
#6      _RawReceivePort._handleMessage (dart:isolate-patch/isolate_patch.dart:192:12)

  stdout:



Building native assets failed. See the logs for more details.

[KomTak001]

Here is some additional information:

flutter pub cache clean

The same error occurs even after running this command.

Please kindly review this.
Also, please let me know if there is any additional information that needs to be coordinated.

Thank you for your time and assistance!

[KomTak001]

First, I apologize for any confusion caused by my previous comment. I previously suggested using dependency_overrides as a potential workaround, but after further testing, I realized it does not resolve the issue and was misleading.

To clarify: I confirmed that this build error occurs during a standard flutter run, completely independent of dependency_overrides.

I hope this extra context helps with troubleshooting!

[KomTak001]

Downgrading to velopack_flutter: 0.1.0 worked for me without this problem.

• Environment:
  • velopack_flutter: 0.1.0
  • Flutter: 3.44.4 / Dart: 3.12.x
  • Platform: macOS (likely reproducible on Windows/Linux as well)

It seems like this issue might have been introduced in a version after 0.1.0. Hope this helps with pinpointing the cause!