Apparent deadlock setting optional Shared property to nil

[humblehacker]

Please see: https://github.com/humblehacker/TCASharedState2

In this example, I have a reducer with two children. The first has an optional shared property, while the second has a non-optional. Tapping the "Toggle" button should toggle the optional property between 0 and nil, but when it attempts to set the property to nil, the app freezes.

Oddly, this only happens if there is at least one other shared property in the app. To see this, comment out Child2View from the body of ExampleView, and try again -- the app no longer freezes.

So, my question is, what am I doing wrong?

Note that this and my previous bug report turned discussion were discovered while attempting to isolate the source of a problem encountered while using shared state in my app.

[mbrandonw]

Hi @humblehacker, thanks for the report. Yeah this one is a real issue, and we should have made withLock run on the @MainActor from the beginning. We thought about making @Shared main actor entirely, but that seemed to be going too far. However, withLock definitely needs to be @MainActor.

I have a fix PR'd here and it will be released with 1.12.