Client shows error message after disconnecting from server

[miguelgrinberg]

Discussed in miguelgrinberg/python-socketio#1300.

When the client disconnects itself from the server, an error message appears before exit. The error message can be one of two possibilities:

Unexpected error decoding packet: "Invalid empty packet received", aborting

Unexpected error receiving packet: "[Errno 9] Bad file descriptor", aborting

The async client reports a slightly different one:

Server sent unexpected packet 256 data None, aborting