[dwds] ext.flutter.debugDumpApp: (-32603) Unexpected DWDS error for callServiceExtension: Unexpected error from chrome devtools

From flutter `stable/3.19.3` which has `dwds: 23.0.0+1`: https://github.com/flutter/flutter/blob/3.19.3/packages/flutter_tools/pubspec.yaml#L17

```
RPCError: ext.flutter.debugDumpApp: (-32603) Unexpected DWDS error for callServiceExtension: Unexpected error from chrome devtools:text: Uncaught (in promise)exception: preview: null description: null type: string value: Unexpected null value.attempted JS eval: `require("dart_sdk").developer.invokeExtension( "ext.flutter.debugDumpApp", JSON.stringify({}));`
at new _OutstandingRequest(vm_service.dart:265)
at VmService._call.(vm_service.dart:1771)
at VmService._call(vm_service.dart:1783)
at VmService.callServiceExtension(vm_service.dart:1733)
at FlutterVmService._checkedCallServiceExtension(vmservice.dart:868)
at FlutterVmService.invokeFlutterExtensionRpcRaw(vmservice.dart:887)
at FlutterVmService.flutterDebugDumpApp(vmservice.dart:614)
at ResidentHandlers.debugDumpApp(resident_runner.dart:681)
at (async)
at TerminalHandler.processTerminalInput(resident_runner.dart:1837)
at (async)
```

This is *not* a top crasher, FYI.

Start by reproducing the failure with Flutter stable/3.19.3 and dwds 23.0.0+1, then trace the callServiceExtension path described through vm_service.dart and resident_runner.dart. Done means ext.flutter.debugDumpApp completes without the Chrome DevTools unexpected-null error.

Written by the indexing model from the issue text.