readonly stopReason is not threadsafe

[bluegaspode]

Just synthesizing a readonly stopReason property is not thread-safe.

In all the AudioStreamers-Code the state is set first, followed by the stopReason.
Upon setting the state, the main thread gets a notification - if it then reads the stopReason it might see an old value, as the actual stopReason might have not been set yet.

At least the read-access to the stopReason should be synchronized - so the main-thread won't see stale data.
Or you change the order - set the stopReason first, followed by the state.