Cannot delete the last item in a `list` in a theme

Looks like there's a glitch where the last item in a list theme setting cannot be deleted.

Steps to reproduce:

1. Install Grav + Admin.
2. Install the Hypertext theme, a bare-bones theme with a list item in the 3rd tab. Theme blueprint YAML file, see line 266.
3. Add a few off-site links. Save.
4. Delete all but one link. Save.
5. Delete the last link. Save.

Expected Behavior: The list will be saved as empty. Actual Behavior: The page refreshes and the last list item is still in the list.

What I've tried

1. Double checked that the permissions on the /user/config/themes/hypertext.yaml file are correct and editable by the host user/group. No change.
2. Double checked that there are no "Default" links in the hypertext.yaml file that comes with the theme, that might be overwriting the emptiness with some default. Nothing there.