Sleeping in a custom dimension with "natural" set to false causes crash

The bug

When creating a custom dimension in a datapack, setting "natural" to false and "bed_works" to true causes a fatal error to console when a player tries to sleep. Despite it being logged as a fatal error, the game doesn't crash, but players are unable to sleep.

Attached is a world that demonstrates the issue, and a datapack that adds a dimension affected by it.

Code analysis

Code analysis by apple502j can be found in this comment.