The Bug:

Buried treasure can create invalid block entities when generating in the location same as a block entity.

When a buried treasure chest is generated, it duplicates the block it replaces to the sides and on top if there is air. This is a problem because in some cases, this can cause spawners from mineshafts to be duplicated, however, the spawners are empty

Steps to Reproduce:

1. Go to a newly generated chunk, go to 9, ~, 9 (chunk coordinates).
2. Stand on the ground and summon some air below you using the command provided below.

   /fill ~-2 ~-4 ~-2 ~2 ~4 ~2 air

3. Fly up a few blocks, but don't change your "x" or "z" coordinate.
4. Summon a cave spider spawner and then a buried treasure by using the commands provided below.

   /execute positioned over world_surface run setblock ~ ~ ~ minecraft:spawner{SpawnData:{entity:{id:"minecraft:cave_spider"}}}

   /place structure minecraft:buried_treasure ~ ~ ~

5. If the chest was placed under the spawner run the command provided below.

   /execute positioned over world_surface run clone ~-2 ~-1 ~-2 ~2 ~-1 ~2 ~-2 ~-2 ~-2 replace move

6. Take note as to whether or not buried treasure can create invalid block entities when generating in the location same as a block entity.

Observed Behavior:

Observe that the buried treasure chest is surrounded on top and to the sides by empty spawners.

Expected Behavior:

If the said block is a block entity, the game should detect this and use a fallback block instead.