Comment 2 for bug 859060

StacktraceTop:
 g_type_check_instance_is_a (type_instance=<optimized out>, iface_type=<optimized out>) at /build/buildd/glib2.0-2.29.92/./gobject/gtype.c:3952
 g_object_get (_object=0x7fa9e6030ae0, first_property_name=0x7fa9d4a8e3be "volume") at /build/buildd/glib2.0-2.29.92/./gobject/gobject.c:1881
 gst_play_sink_get_volume (playsink=0x7fa9e5d08140) at gstplaysink.c:806
 gst_play_bin_get_property (object=0x7fa9e5d04a20, prop_id=<optimized out>, value=0x7fff7410b4d0, pspec=<optimized out>) at gstplaybin2.c:2009
 object_get_property (value=0x7fff7410b4d0, pspec=<optimized out>, object=0x7fa9e5d04a20) at /build/buildd/glib2.0-2.29.92/./gobject/gobject.c:1138