remove some more asserts. nicfit have a look if you really need one

src/dialogs.py

@@ -989,7 +989,6 @@ class PopupNotificationWindow:
 			ev = gajim.get_first_event(self.account, self.jid, self.msg_type)
 			gajim.interface.roster.open_event(self.account, self.jid, ev)
 		else: # chat or pm
-			assert(self.msg_type == 'chat' or self.msg_type == 'pm')
 			gajim.interface.handle_event(self.account, contact.jid, self.msg_type)
 
 		self.adjust_height_and_move_popup_notification_windows()

src/message_control.py

@@ -69,7 +69,7 @@ class MessageControl:
 		return True
 	def shutdown(self):
 		# NOTE: Derived classes MUST implement this
-		assert(False)
+		pass
 	def repaint_themed_widgets(self, theme):
 		pass # NOTE: Derived classes SHOULD implement this
 	def update_ui(self):