make appservice more resilient

service.py

@@ -223,8 +223,12 @@ class Appservice:
 def receive_messages(
     appservice: Appservice, msg_queue: message_queue.MessageQueue
 ):
+    while True:
+        try:
             for message in msg_queue:
                 appservice.process_message(message)
+        except Exception as e:
+            LOG.exception(e)
 
 
 def main():