Its a bug that can't be done in vanilla minecraft

A Villager Trade That Can't Be Done.

What I expected to happen was there would be a normal trade but there is an impossible one.

What actually happened was I wanted to get the max trade for the Librarian and I came across a trade that cant be done.

1. Trade with a Librarian to get this trade.
2. For me it was the last trade
3. 1 Book and 67 Emeralds For 1 Enchanted Book 'Power V'