Check entity count adds and mark entities removed as needed

Spigot-Server-Patches/Check-entity-count-additions-and-mark-entities-remov.patch

@@ -0,0 +1,32 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Zach Brown <1254957+zachbr@users.noreply.github.com>
+Date: Fri, 22 Apr 2016 20:34:21 -0500
+Subject: [PATCH] Check entity count additions and mark entities removed
+
+
+diff --git a/src/main/java/net/minecraft/server/Chunk.java b/src/main/java/net/minecraft/server/Chunk.java
+index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
+--- a/src/main/java/net/minecraft/server/Chunk.java
++++ b/src/main/java/net/minecraft/server/Chunk.java
+@@ -0,0 +0,0 @@ public class Chunk {
+             k = this.entitySlices.length - 1;
+         }
+ 
++        // Paper start - Try to catch plugins doing indecent things
++        if (entity.aa && entity.getChunkX() == this.locX && entity.getChunkY() == k && entity.getChunkZ() == this.locZ) {
++            throw new IllegalStateException("Hey Jackass don't do that.");
++        }
++        // Paper end
++
+         entity.aa = true;
+         entity.ab = this.locX;
+         entity.ac = k;
+@@ -0,0 +0,0 @@ public class Chunk {
+         } else if (entity instanceof IInventory) {
+             inventoryEntityCounts[i]--;
+         }
++        entity.aa = false; // You aren't added to chunk anymore
+         // Paper end
+         // Spigot start - decrement creature type count
+         // Keep this synced up with World.a(Class)
+--