Move writer.close() after writer_coro is done

hbmqtt/mqtt/protocol/handler.py

@@ -127,8 +127,8 @@ class ProtocolHandler:
     def stop(self):
         self._running = False
         yield from self.outgoing_queue.put("STOP")
-        yield from self.writer.close()
         yield from asyncio.wait([self._writer_task, self._reader_task], loop=self._loop)
+        yield from self.writer.close()
         # Stop incoming messages flow waiter
         for packet_id in self.session.incoming_msg:
             self.session.incoming_msg[packet_id].cancel()