Steps to reproduce:

1. Level fletcher villagers until any tipped arrow trade is visible
2. Hover over the offered item to inspect it

Sidenote: The stacks of unstackable items are kind of unnatural too

Looking back at it the fletcher trades are almost as old as this repo. They definitely need some more love.

I will be digging through the trades the coming week to weed out and fix these old placeholders with better trades. Thanks for pointing them out!

This and a multitude of other problems should now be resolved in 0.2.0. Should you find any more, definitely open another issue
Cheers