Long story short

ws.send_json() fails with this warning: WARNING -- asyncio.write : socket.send() raised exception.
ws is from aiohttp.ClientSession().ws_connect()

Expected behaviour

An exception should have be raised along with a traceback message, but nothing happened.

Actual behaviour

It shows the warning and does nothing.

Steps to reproduce

You can see the code here
As far as I know, there is no exact way of reproducing it. You just wait a bit for the bug to appear, likely due to some connection errors along the way?

Your environment

aiohttp 3.3.2
Ubuntu 16.04 LTS