The Witness: Fix extremely late crash when Nothing items exist

[NewSoupVi]

In the area hint code, I forgot to check item is None before doing item.player == world.player in a couple of places. This caused an unnecessary crash when Nothing items exist.

Tested: New unit test (Edit: That is no longer part of the PR)

[alwaysintreble]

i disagree with this on principle. there should be no unfilled locations when fill is finished. #2830

[NewSoupVi]

i disagree with this on principle. there should be no unfilled locations when fill is finished. #2830

Idk how to respond to that. Makes sense, I guess. Witness is fine with unfilled locations and right now they're still "a thing" so

If that gets merged I guess I'll close this

[NewSoupVi]

Simplified the change & decided to get rid of the unit test.
It's now one additional line that protects against this for now and wouldn't cause problems in the future
Maybe that's less controversial, iono
(Credit to Exempt-Medic for thinking of the simpler change)

[Exempt-Medic]

It's one line. I would personally much rather have #2830 but this is one line, and if this gets merged first, it can just be undone in a bigger PR that undoes the other places Witness accounts for this