The last 0 players you rewarded is the empty set
It works, although not in the way you expect.
Originally you could only reward an individual twice, after 5 WP's. This has now been changed so you can reward them every WP if you wanted (although that would probably be an abuse unless it was fairly won).
Therefore now the code is selecting the last 0 people, which is 0 people.
We could probably remove this piece on the page, but for the future when we might bring it back, its been kept.