Custom slider widget is visible although "" is returned

Describe the bug
When creating a custom apple script slider widget and making it return "", it is still visible in the Touch Bar, unlike other apple script widgets. Could this be fixed or is there a work around? I would like my slider widget to be visible only in certain cases. Thanks a lot!

Affected input device (e.g. MacBook Trackpad, Magic Mouse/Trackpad, Touch Bar, etc.):
Touch Bar

Device information:

  • Type of Mac: MacBook Pro 13 2018
  • macOS version: 10.14.1
  • BetterTouchTool version: 2.669 (977)