Recent (3.12+) macOS builds crash on exit.

Describe the bug

Since about the first rawaudio builds, i noticed the Jamulus client sometimes crashing when exiting the app. This has been reported along the rawaudio build discussions by several users though no clear link to the patch could be found, so might as well be unrelated.

Also, latest 4.0 beta1 sometimes crashes on my native M1 build, stacktrace by Apple crash reporter is not super helpful but at least dumps some lines about malloc / mutex calls.

What is interesting is, that @ann0see by accident left a Copilot code analysis report of the iOS build in https://github.com/jamulussoftware/jamulus/commit/00e8668136af62cb863929de66cafb08a71fc622#diff-78ed0fa926a94e116646dc6705a0e993e2ab613c66e3fc2d06376096cb6d6e79 which points to the same direction. Nowadays, macOS and iOS/iPadOS on Apple Silicon share a lot of framework and libs, if not even system libs and kernel (not sure). So there might be a relationship to the Copilot report.

To Reproduce

Very hard to reproduce. Install latest 4.0 beta1 on Apple Silicon (M1 Pro for me). Run, exit, run, exit, run, exit... sometimes after a few attempts Apple reports an app crash with dump.

Expected behavior

It does not crash on exit ;-)

Screenshots

n/a

Operating system

macOS 26.5.1 on Apple Silicon M1 Pro

Version of Jamulus

4.0.0 beta1, happens since ~3.11 git versions

Additional context

See discussion here: https://github.com/orgs/jamulussoftware/discussions/3654#discussioncomment-16690159

Inizia con la riproduzione tramite esecuzioni e uscite ripetute sull’ultima build 4.0 beta1 Apple Silicon e raccogli l’output di Apple crash reporter. Confronta i trace malloc/mutex con l’analisi iOS Copilot collegata e la discussione in #3654; il lavoro è completato quando le uscite ripetute non producono più un crash e il comportamento è coperto da evidenze di regressione.