[bug] Setting empty workspaces to hide

[cinghiopinghio]

Hi,

I was quite happy that PR #184 get merged bringing hidden empty workspaces to nwg-panel.
After updating nwg-panel on sway, I wasn't able to get it working from the Panel setting interface.

I discovered that the only way to get it working was to manually edit the configuration file. Otherwise the old default to 1 2 3 4 5 6 7 8 was automatically forced. It may depend on the way the interface interpret an empty field.

Bests

[nwg-piotr]

I'm aware of the issue, but had no time to get a closer look at it. It would be best if the author of #184 tried to fix it @mildred