Strange behaviour around debugger breakpoints inside computeds

[schmellow]

Hi. I'm not sure if this is a bug in mobx, in my code, or something else, so posting here to hopefully get some guidance

The repro: https://github.com/schmellow/mobx-debugger-cycle
This somewhat contrived example mimics the bigger application, which is a huge form, dynamically composed of different of sections. Each section is backed by its own store. The composite state of all sections is pulled up on change (with a delay) and persisted remotely.

Now normally everything works just fine. But if you put a debugger breakpoint (and here i'm using chrome debugger with vscode run & debug configuration), into FooState.state computed/getter, hit that breakpoint (just press a button on the page) and then continue and go out of the getter, mobx will tell you:

[mobx] Encountered an uncaught exception that was thrown by a reaction or observer component, in: 'Reaction[Reaction@3]' Error: [MobX] Cycle detected in computation FooState@1.state: get state() {
    return {
      count: this.count
    };
  }
at die (<redacted>\mobx-debugger-cycle\node_modules\mobx\src\errors.ts:84:15)
at ComputedValue2.get4 [as get] (<redacted>\mobx-debugger-cycle\node_modules\mobx\src\core\computedvalue.ts:207:13)
at ObservableObjectAdministration2.getObservablePropValue_ (<redacted>\mobx-debugger-cycle\node_modules\mobx\src\types\observableobject.ts:122:39)
at FooState.get4 (<redacted>\mobx-debugger-cycle\node_modules\mobx\src\types\observableobject.ts:706:36)
at get fullState (<redacted>\mobx-debugger-cycle\src\App.state.ts:34:16)

The whole computed chain is broken after that, until app reload.
Breakpoints inside actions cause no issues.
Have anybody encountered something like this? Can something be done, apart not breaking inside computed-related stacks ever?

[schmellow]

After playing around a bit, it seems that pulling the "root" computed out into a simple standalone function solves the issue (demoed in v2 branch).
I wonder what i lose by going this way apart from computed's caching which is not particularly relevant in this usage pattern. Threw together a similiar reorganisation on a bigger codebase and don't see any behavioral differences.

Still curious about what is causing the issue for the original. Debugger touching stack/closures inappropriately and triggering a computation?