The bug

The server crashes upon replacing soul sand with a magma block or replacing a magma block with soul sand under a tall bubble column (tested with 2032 block tall water).

Discovered while testing the fix of MC-214082.

A crash report is attached, as well as the world generation settings file used to create the world.

How to reproduce

World setup

1. Select Singleplayer → Create New World
2. Set your Game Mode to Creative, and make sure cheats are allowed
3. Select More World Options... → Import Settings, and import the 216363.json file
4. Select Create New World

The bug

1. Run the command:

   /fill ~ 1 ~ ~ 2031 ~ water

2. Run the command:

   /setblock ~ 0 ~ soul_sand

3. Run the command:

   /setblock ~ 0 ~ magma_block

   Crash