Squash exceptions when recovering from a disconnected COM port.

[SeanCline]

Thanks for this awesome project! I've been using it for months now.

This change squashes the IOException that sometimes happens when calling serialPort.close() on a COM port which no longer exists. This allows Adrilight to recover from USB disconnects more gracefully.

Here's how that unhandled exception looks on my system:

My use-case might not be that common. My Teensy 3.0 is plugged into my monitor's USB port so it sees a lot of power cycles. Each time, I have to manually restart adrilight.exe. Not a big deal, but allowing Adrilight to recover from this situation solves a minor nuisance.