Plugin doesn't seem to hand RM4 device being offline

[malwcal]

Describe the bug
On a few occasions I have found the plugin not working with my air conditioner. In home I can turn it on/off and change temperature etc. But the unit itself doesn't respond.

The issue has been that my RM4 has lost its power, and so is offline. But the plugin doesn't seem to detect that, and still lets the home app send commands

Steps to reproduce the behaviour:

1. Unplug RM4
2. Click on air conditioner control in home app
3. Notice the air conditioner doesn't respond (as expected)

Expected behaviour
When the RM4 is unreachable, this should be reflected in the home app as "accessory unreachable" and you should not be able to issue commands.

[MrAsterisco]

This looks like a similar issue to what I'm experiencing. In my case, the device seems offline even if it's not.

I have yet to receive a response from the plugin maintainer.