Certain void worlds fail to spawn the player on the stone platform

The bug

When creating a superflat void world with certain seeds, the player is not spawned on the stone platform. This leads to them instantly falling into the void and dying. Respawning also fails to place the player on the stone platform.

To reproduce

Create a Superflat world with the Void preset, with the seed 4, 4710627461264753701, or 1929256340713261754.