PaperMC/Remapped-Spigot-Server-Patches/0391-Don-t-load-Chunks-from-Hoppers-and-other-things.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 3 Nov 2016 20:28:12 -0400
Subject: [PATCH] Don't load Chunks from Hoppers and other things

Hoppers call this to I guess "get the primary side" of a double sided chest.

If the double sided chest crosses chunk lines, it causes the chunk to load.
This will end up causing sync chunk loads, which will unload with Chunk GC,
only to be reloaded again the next tick.

This of course is undesirable, so just return the loaded side as "primary"
and treat it as a single chest if the other sides are unloaded

diff --git a/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java b/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java
index a4f16b2093c867e9fd1c2e07b67c49c3c5ec7506..df20b3616929657d2e8061159ed97f500b33d192 100644
--- a/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java
+++ b/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java
@@ -29,7 +29,12 @@ public class DoubleBlockCombiner {
                 return new DoubleBlockCombiner.NeighborCombineResult.Single<>(s0);
             } else {
                 BlockPos blockposition1 = pos.relative((Direction) function1.apply(state));
-                BlockState iblockdata1 = world.getBlockState(blockposition1);
+                // Paper start
+                BlockState iblockdata1 = world.getTypeIfLoaded(blockposition1);
+                if (iblockdata1 == null) {
+                    return new DoubleBlockCombiner.NeighborCombineResult.Single<>(s0);
+                }
+                // Paper end
 
                 if (iblockdata1.is(state.getBlock())) {
                     DoubleBlockCombiner.BlockType doubleblockfinder_blocktype1 = (DoubleBlockCombiner.BlockType) typeMapper.apply(iblockdata1);