Comment 1 for bug 1392397

It looks like two nested calls to urf-device-ofono.c:set_soft() provokes this. The second call to set_soft() is made before the callback for the first call has been invoked. Apparently this provokes that the callback for the second one is invoked after the call to the object's dispose().

I think that the fact that we are using the same GCancellable object in both calls makes that the call to g_object_unref() for the DBus proxy in dispose() does not cancel the second callback, so it gets called in the end, but the modem object has already been destroyed.