Sable crashes when two sublevels without collision are spawned near each other

[sophuric]

Context

Steps to reproduce

1. Run /tick freeze
2. Run /sable spawn block air twice, this works with water too, and I assume any other block with no collision
3. Run /tick unfreeze or /tick step

Rust backtrace

No crash report was produced but a rust backtrace was printed so I uploaded that instead

https://mclo.gs/0nEg5Gk