Fixed NPE.

git-svn-id: http://svn.igniterealtime.org/svn/repos/wildfire/trunk@6392 b35dd754-fafc-0310-a699-88a17e54d16e

src/java/org/jivesoftware/util/TaskEngine.java

@@ -10,13 +10,13 @@
 
 package org.jivesoftware.util;
 
+import java.util.Date;
 import java.util.Timer;
 import java.util.TimerTask;
-import java.util.Date;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
+import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
@@ -252,12 +252,16 @@ public class TaskEngine {
      * Shuts down the task engine service.
      */
     public void shutdown() {
+        if (executor != null) {
             executor.shutdownNow();
             executor = null;
+        }
 
+        if (timer != null) {
             timer.cancel();
             timer = null;
         }
+    }
 
     /**
      * Wrapper class for a standard TimerTask. It simply executes the TimerTask