Log null TileEntity Owner.

Should prevent a crash and provide some info on the location.

CraftBukkit-Patches/0138-Log-null-TileEntity-Owner.patch

@@ -0,0 +1,29 @@
+From 336e47f7667c88b93d2270fc264bd0cfffe1b307 Mon Sep 17 00:00:00 2001
+From: md_5 <git@md-5.net>
+Date: Sun, 20 Apr 2014 11:16:54 +1000
+Subject: [PATCH] Log null TileEntity Owner
+
+
+diff --git a/src/main/java/net/minecraft/server/TileEntity.java b/src/main/java/net/minecraft/server/TileEntity.java
+index 78e17d7..19d008c 100644
+--- a/src/main/java/net/minecraft/server/TileEntity.java
++++ b/src/main/java/net/minecraft/server/TileEntity.java
+@@ -177,7 +177,14 @@ public class TileEntity {
+ 
+     // CraftBukkit start - add method
+     public InventoryHolder getOwner() {
+-        org.bukkit.block.BlockState state = world.getWorld().getBlockAt(x, y, z).getState();
++        // Spigot start
++        org.bukkit.block.Block block = world.getWorld().getBlockAt(x, y, z);
++        if (block == null) {
++            org.bukkit.Bukkit.getLogger().log(java.util.logging.Level.WARNING, "No block for owner at %s %d %d %d", new Object[]{world.getWorld(), x, y, z});
++            return null;
++        }
++        // Spigot end
++        org.bukkit.block.BlockState state = block.getState();
+         if (state instanceof InventoryHolder) return (InventoryHolder) state;
+         return null;
+     }
+-- 
+1.9.1
+