Would like to propose introducing an sio.ErrXRun error which can be returned from sio linked sound.{Source,Sink,Duplex} to handle xruns (under-runs for playback, over-runs for capture)

This would be in combination with a Source,Sink,Duplex wrappers that handle sio.ErrXRun and
don't ever return them.

The error itself would provide timing information

It would also require interface documentation changes in module zc/sound, as for now the existence of an error implies unrecoverability (which is nice and simple)