End sign color changing only works for the vanilla character skincolors (and green)

According to this, the end sign is supposed to change color to contrast with the player's current skin color. However, it only actually works if the player is blue, orange, red, or green.

Actually, I think this is because most of the "opposite colors" for the skin colors haven't been filled in yet.

Not a bug, just an unfinished feature. The colors that currently work are White, Silver, Grey, Black, Blue, Orange, Red, Green, and Zim. The rest haven't been filled in yet.

If you want to do some testing and find some "opposite" colors that look good for the other skin colors, please do (and tell us what you come up with).