Items with conflicting components disappear entirely instead of attempting to resolve the conflict

Currently the only conflicting components are Max Stack Size and Max Damage. Items with both these components can exist, but in many cases where the conflict is detected, they are instantly deleted in a way that doesn’t really resolve the issue.

Spawning an item with conflicting components cannot be done using /give, but they can be obtained when they already exist in the world, or are spawned using /data modify to create them. To do so, you could drop any item with durability, such as a pickaxe, then run /data modify @n[type=item] Item.components.”minecraft:max_stack_size” set value 99. This behavior is Won’t Fix per MC-301423.

Other than durability decreasing in the whole stack at once, items spawned this way work just fine. If a validation check has to be run, such as the one added to the ItemStack and Item.Properties classes in 26.1, the expected result would be for the item to remove the conflicting parts of its data. If an item has Max_Stack_Size, automatically remove Max_Damage, or vice versa.

However, the current behavior is that, in the few contexts that the validation check is run, the item will be forcefully replaced with an empty itemstack of air, including when an empty stack isn’t supported. (For example this validation check can run in the bundle and leads to another bug, MC-306072, which causes the client to crash because bundles cannot contain air.)

This is much more destructive to preexisting worlds with custom component-modified items that don’t meet validation criteria. (It is also less consistent with the way other types of data are handled. When data modifying an entity to have an invalid tag, only that invalid tag is removed, not the entire entity.) Items shouldn’t just disappear on their own.