LockDrop

This mod allows you to lock an item to prevent it from being dropped from your inventory.
Sometimes you accidentally press “Q” and throw an important item into the void, lava, a cactus, or someone’s farm on the server.

Just press the “L” key while hovering over an item in your inventory, and you won’t be able to drop it without confirmation.

You can also hold an item in your hand and lock it by using the command /lockdrop