Switchbot Curtain 3, crashes when started with --fetch-device-info

[NiekD]

I am using a couple of Switchbot Curtain 3 devices and I would like to get battery- and position information. Unfortunately switchbot-mqtt (latest version) crashes immediately on the first attempt to do so.

Although I don't understand much of the Switchbot API yet, I noticed that the protocols for Curtain 2 and Curtain 3 are different, especially with respect to the device info. I guess that this is the reason for the crashes. If switchbot-mqtt is started without --fetch-device-info, it works well with my Curtain 3 devices.

@fphammerle, Is it possible to add support for Curtain 3 device info?