Getting DWDS error when deubg on web

[burhankhanzada]

Getting DWDS error when deubg on web on every object which i what to see properties

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    • Framework revision 9e1c857886 (5 days ago), 2023-11-30 11:51:18 -0600
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! Doctor found issues in 1 category.

[kNoAPP]

I am also having this issue (Flutter 3.16.0/Chrome/Windows 11).

[BenjiFarquhar]

I also have this issue while debugging web in vs code.

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.16.0, on macOS 14.1.2 23B92 darwin-arm64, locale en-GB)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 15.0.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2022.3)
[✓] IntelliJ IDEA Community Edition (version 2023.2.2)
[✓] VS Code (version 1.84.2)
[✓] Connected device (5 available)
[✓] Network resources

• No issues found!

[elliette]

I fixed the cast error in #2303 but have continued investigating because I want to understand why this is happening when debugging from VS Code but not from DevTools.

This happens when inspecting a Flutter widget, a widget's state or the build context. I haven't been able to reproduce for any other objects.

I added some logging in DWDS to the calls to getObject, and see that when a widget's State is expanded during inspection, VS Code requests some classes that DevTools does not request:

DevTools:

VS Code:

One of those classes is Object_Diagnosticable, and it is this class that is the problem. When we try to evaluate it here we get a null result value. With #2303, we are simply turning a null result into an empty map to suppress any errors, but ideally I would like to return null (which will throw an exception in the getObject call):

getObject: (-32603) Unexpected DWDS error for getObject: Exception: Could not construct class: [ClassRef id: classes|dart:core|Object_Diagnosticable, name: Object_Diagnosticable, library: [LibraryRef id: dart:core, name: dart:core, uri: dart:core]]
#0      new _OutstandingRequest (package:vm_service/src/vm_service.dart:265:34)
#1      VmService._call.<anonymous closure> (package:vm_service/src/vm_service.dart:1771:25)
#2      VmService._call (package:vm_service/src/vm_service.dart:1783:8)
#3      VmService.getObject (package:vm_service/src/vm_service.dart:1003:7)
#4      ProtocolConverter._getterNamesForClassHierarchy (package:dds/src/dap/protocol_converter.dart:740:25)
<asynchronous suspension>
#5      ProtocolConverter.convertVmInstanceToVariablesList (package:dds/src/dap/protocol_converter.dart:300:13)
<asynchronous suspension>
#6      DartDebugAdapter.variablesRequest (package:dds/src/dap/adapters/dart.dart:2008:26)
<asynchronous suspension>
#7      BaseDebugAdapter.handle (package:dds/src/dap/base_debug_adapter.dart:141:7)
<asynchronous suspension>

However, that causes VS Code to show only the error:

@DanTup A couple questions - any idea why Dart-Code is requesting the classes (including Object_Diagnosticable) that DevTools is not? And would it make sense for Dart-Code to catch any errors instead of showing them in the UI (and still displaying all the fields / properties that don't throw exceptions)?

[DanTup]

A couple questions - any idea why Dart-Code is requesting the classes (including Object_Diagnosticable) that DevTools is not?

In VS Code we show getters, but since they're not included in the objects (like fields), we have to walk up all of the superclasses and fetch them to get their getters:

https://github.com/dart-lang/sdk/blob/fe8a13d0b3aa4a37e1dbf687a3fb58e3f9aa06ff/pkg/dds/lib/src/dap/protocol_converter.dart#L299

My guess is DevTools doesn't do this?

And would it make sense for Dart-Code to catch any errors instead of showing them in the UI (and still displaying all the fields / properties that don't throw exceptions)?

Yes, I think this is a bug. Probably here:

https://github.com/dart-lang/sdk/blob/fe8a13d0b3aa4a37e1dbf687a3fb58e3f9aa06ff/pkg/dds/lib/src/dap/protocol_converter.dart#L739-L740

We should have error handling so that failing to fetch a single object doesn't fail the whole thing (if you're not already making changes in there and want me to fix, please open an SDK and assign to me and I'll take a look) - although it's not clear to me why that particular class isn't valid to call 🤔

[elliette]

Yes, I think this is a bug. Probably here:

https://github.com/dart-lang/sdk/blob/fe8a13d0b3aa4a37e1dbf687a3fb58e3f9aa06ff/pkg/dds/lib/src/dap/protocol_converter.dart#L739-L740

We should have error handling so that failing to fetch a single object doesn't fail the whole thing (if you're not already making changes in there and want me to fix, please open an SDK and assign to me and I'll take a look) - although it's not clear to me why that particular class isn't valid to call 🤔

SG! I opened https://dart-review.googlesource.com/c/sdk/+/342704 for a quick fix

[elliette]

Update: we are working on getting this fixed for everyone.

In the meantime, you can use the following workaround:

From your VS Code settings, got to Extensions > Dart > Run and Debug and then uncheck "Evaluate Getters in Debug Views":

[elliette]

We should have error handling so that failing to fetch a single object doesn't fail the whole thing (if you're not already making changes in there and want me to fix, please open an SDK and assign to me and I'll take a look) - although it's not clear to me why that particular class isn't valid to call 🤔

Hmm it seems like DWDS is looking for it in the wrong library (so it probably is valid to call). I've opened: #2314

[Miiite]

Update: we are working on getting this fixed for everyone.

In the meantime, you can use the following workaround:

From your VS Code settings, got to Extensions > Dart > Run and Debug and then uncheck "Evaluate Getters in Debug Views":

I may have misunderstood something, but I don't get why the suggested workaround actually is one ?

I unchecked the specified VSCode setting, and yet in this breakpoint :

I have the following error either in the "variables" tab, or in the "watch" tab

[Reprevise]

Update: we are working on getting this fixed for everyone.

In the meantime, you can use the following workaround:

From your VS Code settings, got to Extensions > Dart > Run and Debug and then uncheck "Evaluate Getters in Debug Views":

This workaround didn't solve the issue for me. After unchecking the setting, and restarting VS Code, I still get the DWDS cast error (unless that's not what it's meant to solve).

[elliette]

This hotfix went out today, so this should now be fixed on Flutter stable. See https://groups.google.com/g/flutter-announce/c/fhCMZHGW36A/m/MeaT3_KiAAAJ

Please run flutter upgrade to upgrade to Flutter 3.16.6

Thank you for your patience!