volumefeedback: guard against null local mixer device
This fixes https://bugs.kde.org/show_bug.cgi?id=436619, as far as I can tell.
I can't really comment on why the pointer would be null, but crashing is definitely bad.
This fixes https://bugs.kde.org/show_bug.cgi?id=436619, as far as I can tell.
I can't really comment on why the pointer would be null, but crashing is definitely bad.