Don't force disconnect when receiving invalid XML from server
As title says, not forcing disconnect when an invalid XML is received from server would be nice, as it can break people's connection (and prevent them from reconnecting) to their XMPP servers if for some reason server is returning invalid XML (which is exactly what's weirdly happening with one of our MUCs at the moment. I'm trying to figure out what it's caused by (might be ejabberd, pidgin or nbxmpp), but in any case here's 3 cases of this causing a DoS on gajim).
Relevant code: https://dev.gajim.org/gajim/python-nbxmpp/blob/master/nbxmpp/dispatcher_nb.py#L300