Describe the bug
If I add a Custom AppleScript Slider to my Touch Bar setup, it comes with a default script of
return "0.5"
for the initial slider value. If I change it in any way (replace it or even just set the value to 0.6) and click "Save", the changes are not saved—open "Advanced Configuration" again, and the script will always have reverted to the above. Makes using the slider kind of difficult. 
Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):
Touch Bar.
Device information:
- Type of Mac: 2017 MBP
- macOS version: 10.13.5
- BetterTouchTool version: 2.512
