java.lang.NullPointerException
   at javax.swing.CellRendererPane.addImpl(CellRendererPane.java:85)
   at java.awt.Container.add(Container.java:363)
   at javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1345)
   at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1294)
   at javax.swing.plaf.basic.BasicListUI.getPreferredSize(BasicListUI.java:561)
   at javax.swing.JComponent.getPreferredSize(JComponent.java:1634)
   at javax.swing.ScrollPaneLayout.layoutContainer(ScrollPaneLayout.java:769)
   at java.awt.Container.layout(Container.java:1419)
   at java.awt.Container.doLayout(Container.java:1408)
   at java.awt.Container.validateTree(Container.java:1505)
   at java.awt.Container.validateTree(Container.java:1511)
   at java.awt.Container.validateTree(Container.java:1511)
   at java.awt.Container.validateTree(Container.java:1511)
   at java.awt.Container.validate(Container.java:1478)
   at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:670)
   at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1635)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:646)
   at java.awt.EventQueue.access$000(EventQueue.java:84)
   at java.awt.EventQueue$1.run(EventQueue.java:607)
   at java.awt.EventQueue$1.run(EventQueue.java:605)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:616)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:158)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)