Crash with _CFAssertMismatchedTypeID when browsing for peers stops

[insidegui]

This crash manifests itself when stop() is called on MultipeerTransceiver during the lifetime of the application. It usually takes multiple starts/stops for the crash to be reproduced. I can reproduce it reliably in macOS 11.4 and 12 beta 2.

Searching for this assertion produced this thread in the Apple Developer Forums, which seems to indicate that it's some problem with the internal implementation of MultipeerConnectivity, not something caused by improper use of the API.

In my testing, it seems to only occur when browsing is stopped and restarted multiple times with the same instance of MCNearbyServiceBrowser. If the browser is destroyed and reconstructed, it doesn't occur. Therefore, the workaround will be implemented in MultipeerKit so that it destroys the browser when stop() is called, and creates a new one if resume() is called after that.