java.lang.NullPointerException
   at javax.swing.CellRendererPane.addImpl(CellRendererPane.java:102)
   at java.awt.Container.add(Container.java:410)
   at javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1362)
   at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1311)
   at javax.swing.plaf.basic.BasicListUI.getPreferredSize(BasicListUI.java:578)
   at javax.swing.JComponent.getPreferredSize(JComponent.java:1660)
   at javax.swing.ScrollPaneLayout.layoutContainer(ScrollPaneLayout.java:790)
   at java.awt.Container.layout(Container.java:1503)
   at java.awt.Container.doLayout(Container.java:1492)
   at java.awt.Container.validateTree(Container.java:1688)
   at java.awt.Container.validateTree(Container.java:1697)
   at java.awt.Container.validateTree(Container.java:1697)
   at java.awt.Container.validateTree(Container.java:1697)
   at java.awt.Container.validate(Container.java:1623)
   at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:653)
   at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1620)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:721)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:682)
   at java.awt.EventQueue$3.run(EventQueue.java:680)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:691)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)