prevent traceback when changing resource of a control when there is no event...

prevent traceback when changing resource of a control when there is no event for the account at all. Fixes #5375

src/common/events.py

@@ -163,6 +163,8 @@ class Events:
 		del self._events[account][jid]
 
 	def change_jid(self, account, old_jid, new_jid):
+		if account not in self._events:
+			return
 		if old_jid not in self._events[account]:
 			return
 		if new_jid in self._events[account]: