Ignores socket errors that occur during shut_down

[alindeman]

If the socket has already disconnected, e.g., we don't want to raise another error (see #34, #20) when trying to close it cleanly.

Scenario:

1. The socket disconnects for an unexpected reason.
2. An exception is raised when we try to write to it.
3. The on_exception handler is called, which starts shutting the robot down.
4. The shut_down method is called.
5. By trying to close the socket cleanly, we attempt to write to it again, causing another exception (e.g., IOError or Errno::ECONNRESET)
6. The new exception bubbles up and lita doesn't exit cleanly.

I think we should log, but not re-raise, exceptions during shut down of the connector.

WDYT @MattMencel @sjernigan @jimmycuadra

[jimmycuadra]

Good idea! It might be worth trying to determine which exceptions would actually occur in this scenario that we want to ignore rather than doing a blanket rescue. I've been thinking about this for Lita core as well—rescuing absolutely everything is pretty dangerous. Granted in this situation we're about to shut the program down anyway, but it still makes me nervous to be potentially ignoring critical errors from the system.

[alindeman]

Good idea! It might be worth trying to determine which exceptions would actually occur in this scenario that we want to ignore rather than doing a blanket rescue. I've been thinking about this for Lita core as well—rescuing absolutely everything is pretty dangerous. Granted in this situation we're about to shut the program down anyway, but it still makes me nervous to be potentially ignoring critical errors from the system.

@jimmycuadra: Seems reasonable to me! If I do a bit more testing and flesh out the types of exceptions that occur in the scenario, is the PR otherwise acceptable? If so, I'll get right on that.

[jimmycuadra]

Yeah, absolutely. Thank you for your work!

[alindeman]

Yeah, absolutely. Thank you for your work!

@jimmycuadra No problem. I've updated the catch to be more specific.

[jimmycuadra]

Thanks, Andy! Hopefully this will help with the disconnection problem people have been having.

[jimmycuadra]

Released in v3.0.2: https://github.com/litaio/lita-hipchat/releases/tag/v3.0.2