UnloadWorld-Bugfix

src/de/warking/bausystem/world/LagDetectorRunnable.java

@@ -22,7 +22,7 @@ class LagDetectorRunnable implements Runnable {
 
     @Override
     public void run() {
-		if (world == null) {
+		if (world == null || task.isCancelled()) {
 			task.cancel();
 			return;
 		}