Bugfix: client_handler.py

[miili]

More defensive closing of a broken connection.

We saw a rant of messages on instable/unreliable connections:

2022-07-28T08:23:17.804100764Z WARNING:asyncio:socket.send() raised exception.
2022-07-28T08:23:17.804102147Z DEBUG:amqtt.mqtt.protocol.handler:Broker closed connection
2022-07-28T08:23:17.804103500Z WARNING:asyncio:socket.send() raised exception.
2022-07-28T08:23:17.804104932Z DEBUG:amqtt.mqtt.protocol.handler:Broker closed connection
2022-07-28T08:23:17.804106265Z WARNING:asyncio:socket.send() raised exception.
2022-07-28T08:23:17.804107587Z DEBUG:amqtt.mqtt.protocol.handler:Broker closed connection
2022-07-28T08:23:17.804108930Z WARNING:asyncio:socket.send() raised exception.

These were thrown 10 k/s and flooded logs and the buffer, leading to an instable system.

I think this is due to an unhandled closed connection. Please review the attached MR.

[miili]

ping @FlorianLudwig

[miili]

ping @FlorianLudwig

[FlorianLudwig]

@miili sorry for the long delay, looks good to me! thank you very much