first run on clean MATE system doesn't recognize tablet

[skomra]

Here is the error message you see on exit after the first run on a clean MATE system

Traceback (most recent call last):
File "/usr/local/wacom-gui/wacom-gui.py", line 442, in closeEvent
self.updateConfigs()
File "/usr/local/wacom-gui/wacom-gui.py", line 372, in updateConfigs
if pad != self.configs[self.dev][self.config]['pad']['buttons']: