Reported by Nicola Fontana, Dec 21, 2012
Currently the error state is hold internally in some object (most notably inside NtdDevice) and can be queried with a bunch of APIs. This is somewhat inconvenient (you should always expose the device on every object uses it to be able to access the error state) and unfamiliar to what GLib/GObject is used to. Append a GError to every function that can fail, handling it in the usual way. Drop the internal GError and the custom code that manages it.