flutter build web --wasm failed due to RangeError

[teabuff]

General

What bug do you experience? 🐞

I am using flutter_chat_ui in my app, and when I tried to run the flutter build web --wasm which was introduced recently
to build my web app in web assembly, I saw the following errors:

flutter build web --wasm

┌─ New feature ────────────────────────────────────────────────────────────────────────────┐
│   WebAssembly compilation is new. Understand the details before deploying to production. │
│   See https://flutter.dev/wasm for more information.                                     │
└──────────────────────────────────────────────────────────────────────────────────────────┘

Compiling lib/main.dart for the Web...
Invalid depfile: /home/user/workspace/tongsui_demo/.dart_tool/flutter_build/2bc6bf09fa388c3aa3580c6c6256f0e7/dart2wasm.d
Invalid depfile: /home/user/workspace/tongsui_demo/.dart_tool/flutter_build/2bc6bf09fa388c3aa3580c6c6256f0e7/dart2wasm.d
Target dart2wasm failed: ProcessException: Process exited abnormally with exit code 64:
*NOTE*: Compilation to WasmGC is experimental.
The support may change, or be removed, with no advance notice.

Exception in InstanceInvocation at file:///home/user/.pub-cache/hosted/pub.dev/flutter_chat_ui-1.6.12/lib/src/widgets/typing_indicator.dart:244:53

Unhandled exception:
RangeError (index): Invalid value: Valid value range is empty: 1
#0      List.[] (dart:core-patch/growable_array.dart:264)
#1      Intrinsifier.generateInstanceIntrinsic (package:dart2wasm/intrinsics.dart:337)
#2      CodeGenerator.visitInstanceInvocation (package:dart2wasm/code_generator.dart:1817)
#3      InstanceInvocation.accept1 (package:kernel/ast.dart:5803)

What behavior is expected? 💡

flutter build web --wasm should be run successfully

Environment info

Please specify the flutter, flutter-chat-ui versions.

flutter: 3.22
flutter-chat-ui: 1.6.12

Platform

Device (e.g. Android emulator, iOS simulator, Samsung Galaxy S21): Chrome 124.0.6367.208

OS version (e.g. iOS 14.5, Android 11): Mac os 14.4.1

Additional context

I think the issue is src/widgets/typing_indicator.dart:244 use author[1] that does not compatible with the wasm requirement.

I modified the code to

    else if (author.length == 2) {
      return '${author.first.firstName} and ${author.last.firstName}';
    }

that fixed the issue and flutter build web --wasm is successful after the change. If you are OK with this method (replace author[1] to author.last), I can create a pull request for it.

[demchenkoalex]

I will check it and release this week. Thanks for raising this!

[demchenkoalex]

yeah this change works and build passes! please note that in the example project I had to remove all dependencies that use ffi cause it crashes with some random error. But I guess you already know that. Change will be included in v1.6.13 release that I will do today or tomorrow morning.

[Rexios80]

I don't see any issue with the code that is failing to compile. Is this a bug in the WASM compiler?

[demchenkoalex]

yes, it is the same issue as here rive-app/rive-flutter#391, because rive also depends on ffi

[osa1]

please note that in the example project I had to remove all dependencies that use ffi cause it crashes with some random error

@demchenkoalex could you commit your changes that remove these dependencies so that I can take a look at the crash reported in the OP and debug?

[mkustermann]

Let's track this issue on the Dart SDK issue tracker (see dart-lang/sdk#55817)

[demchenkoalex]

hey @osa1 sorry for the late reply.

pushed a branch called wasm-error.

in the example folder you can run flutter build web --wasm and it will fail with the original issue. To fix the issue go to the lib/src/widgets/typing_indicator.dart line 245 and change author[1].firstName to author.last.firstName. Prior to this line there is a check that author.length == 2 so there are 2 items always, and they should be accessible by both [0] and [1] indices and first and last properties

[osa1]

Thanks @demchenkoalex. This was fixed by dart-lang/sdk#55817.