pulsesink: Deal with not being able to convert a format to caps
It is possible that PulseAudio adds formats that are not yet supported in pulsesink, and in those cases, we want to gracefully skip them rather than cause an assert on a NULL caps.
It is possible that PulseAudio adds formats that are not yet supported in pulsesink, and in those cases, we want to gracefully skip them rather than cause an assert on a NULL caps.