src/java.desktop/macosx/classes/sun/lwawt/macosx/CTrayIcon.java

@@ -355,11 +355,11 @@
     }
 
     class IconObserver implements ImageObserver {
         @Override
         public boolean imageUpdate(Image image, int flags, int x, int y, int width, int height) {
-            if (image != target.getImage()) // if the image has been changed
+            if (target == null || image != target.getImage()) //if the image has been changed
             {
                 return false;
             }
             if ((flags & (ImageObserver.FRAMEBITS | ImageObserver.ALLBITS |
                           ImageObserver.WIDTH | ImageObserver.HEIGHT)) != 0)