Deleting list field options completely, won't save changes

[Karmalakas]

If I remove all items under Configuration > Languages > Content Language Fallback and click "Save", item just reappears

Grav 1.7.5
Admin 1.10.3

[Karmalakas]

Might be related to this issue

[mahagr]

I can reproduce this with Grav 1.6 and admin 1.9 as well.

[mahagr]

I found the reason, which is that the admin isn't using the form plugin but relies on the old method of merging two arrays together. It is not a reliable method and was replaced everywhere else than in admin.