How to recreate it:
Go into any gamemode, any dimension, and place an anvil.
Get an item with durability, like a Trident, Sword, Armor, or a bow.
Make sure this item has full durability,
Now, open the anvil and put that item in the first slot of the anvil
This will cause your Minecraft to crash.
Crashed on: Diamond Sword, Gold Sword, Chainmail Chestplate, Bow, Crossbow
Continued on: Totem of Undying, (all kinds of) Arrows, books of enchanting
Notices: it has to be full durability, and it crashes on both Windows and Mac, Only works on Multiplayer.
Patched in 1.15.1-pre1