gqrx freezes when audio output device disappears

[akhepcat]

I noticed this on my kubuntu 24.04 workstation:

I start up gqrx to receive from my SDR, and then start up qsstv. Next, I run "catia" so I can pipe the output from gqrx directly into qsstv

This works great, however if qsstv dies or is shut down, gqrx stops responding, because it's "spinlocked" trying to send audio to a non-existent endpoint.

This is repeatable across multiple versions.

Expectation is that output is asynchronous to the GUI, so that the program can select a different audio output, or to exit after flushing outstanding buffers.