Group without admin if the group admin deletes his profile

If a group has only one administrator and that administrator deletes their profile, the group will be admin-less.

The group admin shouldn't be able to delete their profile until they appoint someone else as an admin or delete the group. This should be displayed to the respective group admin as a warning when they want to delete their profile: The profile can only be deleted once you appoint someone as an admin in your group(s) or space(s) or delete the group(s) or space(s).

Groups without a group admin are counterproductive.

This should also apply to leaving the group as a group admin; in this case, too, someone else must first be named as the group admin.