Raise error on Appeal form when "Invite Friends Only" checked but no friends are selected

[elenadanailova]

I actually managed to invite everyone by clicking on CTA button "Invite Friends Only". No friends were added though.

CTA button "Invite Friends Only" should be enabled only if at least 1 friend is added.

I know the Django forms are now made to always appear enabled and rather display error message if something has to be completed. This will work for now as well. The point is I should not be able to invite Everyone if I have selected checkbox "Invite Friends Only".

This is the invitation: https://alpha.qwikgame.org/player/appeal/614/