Placing a block in the middle of an entity on the client side will make it disappear, and on the server side the item is stored in the inventory.

If you try to place a solid block in the middle of an entity, it will cause the block to disappear. Steps to reproduce:

1. Spawn a villager in Creative mode.

2. Try to place a solid block such as a bookshelf in the middle of the villager.

3. If successful, the bookshelf or other solid block will disappear and be invisibly stored in the inventory.