Fix nullpointer exception

src/minecraft/net/minecraft/src/WorldServer.java

@@ -555,9 +555,10 @@ public class WorldServer extends World
     }
     
     public void addExtraChunk(BigInteger x, int y, BigInteger z, ExtendedBlockStorage blockStorage) {
-    	long time = System.currentTimeMillis();
+//    	long time = System.currentTimeMillis();
     	super.addExtraChunk(x, y, z, blockStorage);
 //    	System.out.println(System.currentTimeMillis() - time);
+    	if(thePlayerManager == null || blockStorage.isEmpty()) return;
     	PlayerInstance instance = thePlayerManager.getOrCreateChunkWatcher(x, z, false);
     	if(instance != null) {
     		instance.sendToAllPlayersWatchingChunk(new Packet57ExtraChunk(x, y, z, blockStorage));