What happens:

Running the /clear command while setting the maximally cleared amount to 0 causes the crafting grid in the adventure mode/survival mode inventory to be cleared, regardless of the item type.

What I expected:

The /clear command should not remove any items that are not of the specified type and also should not remove more than the specified maximum. Therefore, clearing 0 of any type should not affect anything except for the command result.

How to reproduce:

1. Set up an unconditional always active repeating command block with clear @a stone 0 set as the command
2. Change your own gamemode to survival
3. Attempt to place any item in the crafting grid slots

-> The item will be removed.