DartVM crashes when a specific breakpoint is hit about sdk

[dcharkes]

Thanks for the report @akemimadoka!

When implementing this, I thought the entries would never be visible from the debugger.

void FinalizerEntry::PrintJSONImpl(JSONStream* stream, bool ref) const {
  UNREACHABLE();
}

https://github.com/dart-lang/sdk/blob/fd1ac98359894e75dfb8ab62a02dc1b764fff075/runtime/vm/object_service.cc#L2068C1-L2070

However, when setting a breakpoint in the code that's run when the finalizer is run, it's iterating over entries, which are then visible the debugger.

I'll make a fix for this.

[aam]

cc @dcharkes

[dcharkes]

@bkonyi How do I add a test for this?

[mraleph]

@bkonyi How do I add a test for this?

You can add tests to service suite. You can set break points, ask stack traces and do whatever stuff.

e.g. https://github.com/dart-lang/sdk/blob/main/runtime/observatory/tests/service/async_generator_breakpoint_test.dart