Folia/patches/server/0012-Block-reading-in-world-tile-entities-on-worldgen-thr.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Sun, 23 Apr 2023 07:08:26 -0700
Subject: [PATCH] Block reading in-world tile entities on worldgen threads

The returned TE may be in the world, in which case it is unsafe
for the current thread to modify or access its contents.

diff --git a/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java b/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java
index 4a3ac7dedf5cb1e76f16ec4f18e82afc717d0ced..44609fb7965a03283e2bb50e483a8f60254de510 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java
@@ -84,6 +84,11 @@ public class ImposterProtoChunk extends ProtoChunk {
     @Nullable
     @Override
     public BlockEntity getBlockEntity(BlockPos pos) {
+        // Folia start - block reading possibly in-world block data for worldgen threads
+        if (!this.allowWrites && !io.papermc.paper.util.TickThread.isTickThread()) {
+            return null;
+        }
+        // Folia end - block reading possibly in-world block data for worldgen threads
         return this.wrapped.getBlockEntity(pos);
     }