Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

A player joining the server is triggering the load of a chunk.

The recreateStructures stage of the chunkload determines that an OTG Woodland Mansion needs to be placed.

The server then crashes when the OTG Woodland Mansion generator tries to find the height of the highest block at the centre of a chunk.

The method (getHighestBlockInCurrentlyPopulatingChunk) that performs this relies on the OTGChunkGenerator.chunkbuffer being populated but I believe that this only happens during chunk generation and it is set to null during a replaceStructures stage.

Expected Behavior

No crash during replaceStructures when a Woodland Mansion needs to be placed.

Which platforms have you reproduced this issue using?

Forge Multiplayer / Forge Singleplayer

OTG Version

OTG 1.12.2-v9.5-R2 (RAD 1.55)

Platform Version

forge-14.23.5.2860

Steps To Reproduce

I'm not sure what circumstances can leave a world in this state but here's a way to reproduce:

1. Create a new singleplayer world with cheats enabled
2. Go to creative mode and fly
3. Use the command /locate Mansion to get the x, z block co-ordinates
4. Teleport to the that location, wait for the generation to complete
5. Save and exit to the menu
6. In the world save find the file <world>/data/Mansion.dat
7. Either:
   • Delete/rename this file
     or
   • Edit the file in an NBT editor and remove all the child nudes under Features
8. Open the world in the game

Log file

Singleplayer Crash:

Log: https://paste.denizenscript.com/View/135845

Crash Report: https://mclo.gs/ZRwKYjd

Multiplayer Crash:

Log Partial: https://paste.denizenscript.com/View/135839

[16:10:47] [Server thread/ERROR] [net.minecraft.server.MinecraftServer]: Encountered an unexpected exception
net.minecraft.util.ReportedException: Exception preparing structure feature
        at net.minecraft.world.gen.structure.MapGenStructure.recursiveGenerate(MapGenStructure.java:75) ~[bbu.class:?]
        at com.pg85.otg.forge.generator.structure.OTGMapGenStructure.generate(OTGMapGenStructure.java:34) ~[OTGMapGenStructure.class:?]
        at com.pg85.otg.forge.world.ForgeWorld.recreateStructures(ForgeWorld.java:1021) ~[ForgeWorld.class:?]
...
Caused by: java.lang.NullPointerException
        at com.pg85.otg.forge.generator.OTGChunkGenerator.getHighestBlockInCurrentlyPopulatingChunk(OTGChunkGenerator.java:501) ~[OTGChunkGenerator.class:?]
        at com.pg85.otg.forge.generator.structure.OTGWoodLandMansionStart.create(OTGWoodLandMansionStart.java:57) ~[OTGWoodLandMansionStart.class:?]
        at com.pg85.otg.forge.generator.structure.OTGWoodLandMansionStart.<init>(OTGWoodLandMansionStart.java:31) ~[OTGWoodLandMansionStart.class:?]

Crash Report: https://mclo.gs/5gWu8Hc

Anything else?

This bug was previously reported: #267

The fix applied may have solved a different bug.