QMediaDevices logs errors

repro:
just calling getAvailableAudioDevices or getDefaultAudioDevice causes this error to be logged:

HALC_ShellObject::HasProperty: initial inner method call failed, Error: 560947818 (!obj)

I'm concerned that this is a real error leaving something in a bad state, evidence being that, in my app at least, logging immediately halts after this, and breakpoints fail to break, see QTCREATORBUG-27507.

1. load the "audiodevices" example project
2. run it
3. look in the "application output" panel when you step over line 83 of audiodevices.cpp