Q[Audio|Media]Recorder error property never reset

Those classes have an error getter and signal, but they lack a property (a detail...).

This issue is that once an error is reported, it's never cleared again as we change the encoder properties.

By example selecting a pair of uncompatible container/audio settings would trigger an error signal to tell about it.

But if i then change those to something correct, the errorString() / error() getters still report errors. The error should be cleared while changing any properties of the recorder.

Also, having a Q_PROPERTY for it would not be luxurious.

Linux/X11/gstreamer.