Check entity count adds and mark entities removed as needed

Spigot-Server-Patches/0145-Check-entity-count-additions-and-mark-entities-remov.patch

@@ -0,0 +1,34 @@
+From cbda3b924454b5badd57f8dc2550d315ca8441bb Mon Sep 17 00:00:00 2001
+From: Zach Brown <zach.brown@destroystokyo.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 5c1685d..88f8ab8 100644
+--- a/src/main/java/net/minecraft/server/Chunk.java
++++ b/src/main/java/net/minecraft/server/Chunk.java
+@@ -661,6 +661,12 @@ 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;
+@@ -711,6 +717,7 @@ 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)
+-- 
+2.8.0
+