Half TCP connection closed error

[ChaitanyaYeole02]

I received this error when I disconnected my charger while a message was still in process.
@villekr This could be changed in the next version.

    async def on_receive(self, *, message: str, context: RouterContext):
        router: Router = self.routers[context.subprotocol]
        try:
            await router.route_message(message=message, context=context)
        except:
            pass

[villekr]

This should be handled correctly in fix #11.