(trunk) gstreamer error breaks the pipe (normal engine), and it's not shown in the dialog

rev3926
normal engine.

When i try to play a track which no longer exists, but it's still in the collection, some problems occur.

-First, the error is not shown in the dialog, i get:

TypeError: Gtk.Label.set_markup() argument 1 must be string, not gst.Message

That's cause, in xl/player/_base.py lines 119-120, we have:

            a = message.parse_error()[0]
            event.log_event('playback_error', self, message)

Maybe it should be(?):
            a = message.parse_error()[1]
            event.log_event('playback_error', self, a)

- Second, if i try to play another track after that, the pipe is broken and i get:

(exaile.py:16919): GStreamer-WARNING **: Element 'bin1' already has parent

I also noticed that the breakage doesn't occur if the "fake-track" is in first position in the playlist.

I also tried with unified engine, but I get inconsistent results, sometimes it happens sometimes not.

I attach the concerned portion of the shell output.