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 f920fabed523906d4dd49c76db58044954880415..af4f06f798125f8b5d79324d99c48ac83727fcda 100644
--- a/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java
+++ b/src/main/java/net/minecraft/world/level/block/DoubleBlockCombiner.java
@@ -25,7 +25,12 @@ public class DoubleBlockCombiner {
                 return new DoubleBlockCombiner.NeighborCombineResult.Single<>(blockEntity);
             } else {
                 BlockPos blockPos = pos.relative(function.apply(state));
-                BlockState blockState = world.getBlockState(blockPos);
+                // Paper start
+                BlockState blockState = world.getBlockStateIfLoaded(blockPos);
+                if (blockState == null) {
+                    return new DoubleBlockCombiner.NeighborCombineResult.Single<>(blockEntity);
+                }
+                // Paper end
                 if (blockState.is(state.getBlock())) {
                     DoubleBlockCombiner.BlockType blockType2 = typeMapper.apply(blockState);
                     if (blockType2 != DoubleBlockCombiner.BlockType.SINGLE && blockType != blockType2 && blockState.getValue(directionProperty) == state.getValue(directionProperty)) {