I have just released version 2.16.3 of the plugin. This is a quick fix for the problem that @npr reported above. The error only happened when opening configuration dialog if the option to configure each device separately was selected on the second tab. This should fix this.
The release notes are:
- Fix: Error when opening configuration and device specific options were being used.
As usual, calibre will announce the update in the next hour or so. And if there are any problems, please report them here.