From 233dec6facb9b9c1c11989bf62e504303c9a4d56 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 31 Mar 2020 03:01:45 -0400
Subject: [PATCH] Fix unregistering entities from unloading chunks

CraftBukkit caused a regression here by making unloading chunks not
have a ticket added and returning unloaded future.

This caused entities who were killed in same tick their chunk is unloading
to not be able to be removed from the chunk.

This then results in dead entities lingering in the Chunk.

Combine that with a buggy detail of the previous implementation of
the Dupe UUID patch, then this was the likely source of the "Ghost entities"

diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
index f80c80957a..3f8f40018d 100644
--- a/src/main/java/net/minecraft/server/WorldServer.java
+++ b/src/main/java/net/minecraft/server/WorldServer.java
@@ -1508,9 +1508,9 @@ public class WorldServer extends World {
     }
 
     private void removeEntityFromChunk(Entity entity) {
-        IChunkAccess ichunkaccess = this.getChunkAt(entity.chunkX, entity.chunkZ, ChunkStatus.FULL, false);
+        Chunk ichunkaccess = entity.getCurrentChunk(); // Paper - getChunkAt(x,z,full,false) is broken by CraftBukkit as it won't return an unloading chunk. Use our current chunk reference as this points to what chunk they need to be removed from anyways
 
-        if (ichunkaccess instanceof Chunk) {
+        if (ichunkaccess != null) { // Paper
             ((Chunk) ichunkaccess).b(entity);
         }
 
-- 
2.26.2