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

最新の 4.0 beta1 Apple Silicon ビルドで、実行と終了を繰り返す再現から始め、Apple crash reporter の出力を収集してください。malloc/mutex トレースを、リンクされている iOS Copilot の分析および #3654 の議論と比較してください。繰り返し終了してもクラッシュが発生しなくなり、その動作がリグレッションの証拠でカバーされれば完了です。