Only use stored chunk ref if it matches current chunk registration

Closes #1197

While this really undoes a lot of the desired performance gains avoiding chunk lookups,
we sadly have to accept this because we are seeing lots of bugs with entities.

Spigot-Server-Patches/Disable-Scoreboards-for-non-players-by-default.patch

@@ -37,7 +37,7 @@ index ec9a87239..b08274d93 100644
  
                          if (scoreboard.addPlayerToTeam(s2, s)) {
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 21118c031..921b442cd 100644
+index a4c5b780c..c620667e0 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Don-t-allow-entities-to-ride-themselves-572.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Don't allow entities to ride themselves - #572
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 0ed9a8413..646a2d673 100644
+index 64e566d3a..f75d57c30 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Don-t-teleport-dead-entities.patch

@@ -7,7 +7,7 @@ Had some issue with this in past, and this is the vanilla logic.
 Potentially an old CB change that's no longer needed.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index e8775e66c..7e992aeaa 100644
+index 843cb3a61..89ea217b9 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Drop-falling-block-and-tnt-entities-at-the-specified.patch

@@ -24,7 +24,7 @@ index 0094d1a87..4da846719 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 137da4255..655340c0b 100644
+index 9d7fe97ce..c7513622e 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Entity-Origin-API.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Entity Origin API
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 655340c0b..a96513e27 100644
+index c7513622e..72efe282b 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Option-to-use-vanilla-per-world-scoreboard-coloring-.patch

@@ -19,7 +19,7 @@ index abc1aabdd..6ea608ba9 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 7e992aeaa..08d872318 100644
+index 89ea217b9..437ae2fa3 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Optional-TNT-doesn-t-move-in-water.patch

@@ -32,7 +32,7 @@ index 067cb233e..06acdaaf0 100644
 +    }
  }
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 0412e183a..9ce691061 100644
+index e860e9c6a..a52cd0728 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Properly-remove-entities-on-dimension-teleport.patch

@@ -22,7 +22,7 @@ requirement, but plugins (such as my own) use this method to
 trigger a "reload" of the entity on the client.
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index fccaebfbd..5d1ea0d55 100644
+index 9f2db9025..a96cdcbc6 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper

Spigot-Server-Patches/Store-reference-to-current-Chunk-for-Entity-and-Bloc.patch

@@ -81,7 +81,7 @@ index 4bbebb25a..68008fe6a 100644
      }
  
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 3a8902bf1..ed090cc50 100644
+index 3a8902bf1..f7750a05c 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper
@@ -90,8 +90,13 @@ index 3a8902bf1..ed090cc50 100644
      // Paper start
 +    private java.lang.ref.WeakReference<Chunk> currentChunk = null;
 +    public Chunk getCurrentChunk() {
-+        final Chunk chunk = currentChunk != null ? currentChunk.get() : world.getChunkIfLoaded(getChunkX(), getChunkZ());
-+        return chunk != null && chunk.isLoaded() ? chunk : null;
++        final Chunk chunk = currentChunk != null ? currentChunk.get() : null;
++        final int cx = getChunkX();
++        final int cz = getChunkZ();
++        if (chunk != null && chunk.isLoaded() && chunk.locX == cx && chunk.locZ == cz) {
++            return chunk;
++        }
++        return world.getChunkIfLoaded(cx, cz);
 +    }
 +    public void setCurrentChunk(Chunk chunk) {
 +        this.currentChunk = chunk != null ? new java.lang.ref.WeakReference<>(chunk) : null;

Spigot-Server-Patches/Vehicle-Event-Cancellation-Changes.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Vehicle Event Cancellation Changes
 
 
 diff --git a/src/main/java/net/minecraft/server/Entity.java b/src/main/java/net/minecraft/server/Entity.java
-index 08d872318..e6a5bc53c 100644
+index 437ae2fa3..17ec10c26 100644
 --- a/src/main/java/net/minecraft/server/Entity.java
 +++ b/src/main/java/net/minecraft/server/Entity.java
 @@ -0,0 +0,0 @@ public abstract class Entity implements ICommandListener, KeyedObject { // Paper