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 b4e05ce176dfc6a2e66b294ed461c32020adf203..10429dfb6f2ec6aaffa7d71c4d32666ec6f65636 100644
--- a/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/ImposterProtoChunk.java
@@ -90,6 +90,11 @@ 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);
     }