Steps to reproduce:

• Have a relationship with a villager that allows you to receive a discount
  • Ex: trade 2 melons instead of 3 for 1 emerald
• Have just enough of one stack of an item in inventory to trade with villager at the discounted price
  • Ex: have 2 melons in inventory
• Attempt to trade with villager

Observed:

• Trade cannot be completed successfully
• Clicking on resulting item (ex: emerald) artificially increases villager EXP
• Clicking on resulting item continuously eventually maxes out trade for that trade session with villager

Desired:

• Trade happens normally

Workaround:

• Have enough items in your inventory to complete the trade at the non-discounted price
  • Ex: have 3 melons in inventory
• Trade with villager works at discounted price
  • Ex: with 3 melons -> trade -> inventory is now 1 melon and 1 emerald