Crash: java.lang.NullPointerException occures when generating some chunks in upgraded world

The Bug:

On upgraded world, when you start generating new chunks near already generated territory(on 1.17.1 and older versions) sometimes game freezes and then crashes

Steps to reproduce:

1. Make a world in 1.17.1
2. Generate a big amount of chunks(like 1000x1000 blocks area)
3. Open this world in 1.18 Pre-release 1
4. Fly and generate new chunks near the end of 1.17.1 chunks
5. After some time of flying in such a trajectory you will see freeze or crash of the game

Additional information:

• This bug is kinda tricky to discover
• I tested this bug in a world with small amount of pre-existed old chunks and there were no crashes
• In the video(Minecraft 2021.11.11), left side are old chunks and right side are new chunks
• Java`s version is 17 because there is a bug with new launcher that crashes your computer when you are using built-in java