java.lang.NullPointerException
   at javax.swing.DefaultRowSorter.convertRowIndexToModel(DefaultRowSorter.java:501)
   at javax.swing.JTable.convertRowIndexToModel(JTable.java:2611)
   at javax.swing.JTable.getValueAt(JTable.java:2686)
   at javax.swing.JTable.prepareRenderer(JTable.java:5703)
   at javax.swing.plaf.basic.BasicTableUI.paintCell(BasicTableUI.java:2072)
   at javax.swing.plaf.basic.BasicTableUI.paintCells(BasicTableUI.java:1974)
   at javax.swing.plaf.basic.BasicTableUI.paint(BasicTableUI.java:1770)
   at javax.swing.plaf.ComponentUI.update(ComponentUI.java:143)
   at javax.swing.JComponent.paintComponent(JComponent.java:752)
   at javax.swing.JComponent.paint(JComponent.java:1029)
   at javax.swing.JComponent.paintChildren(JComponent.java:862)
   at javax.swing.JComponent.paint(JComponent.java:1038)
   at javax.swing.JViewport.paint(JViewport.java:747)
   at javax.swing.JComponent.paintChildren(JComponent.java:862)
   at javax.swing.JComponent.paint(JComponent.java:1038)
   at javax.swing.JComponent.paintToOffscreen(JComponent.java:5124)
   at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1479)
   at javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1410)
   at javax.swing.RepaintManager.paint(RepaintManager.java:1224)
   at javax.swing.JComponent._paintImmediately(JComponent.java:5072)
   at javax.swing.JComponent.paintImmediately(JComponent.java:4882)
   at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:785)
   at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:713)
   at javax.swing.RepaintManager.seqPaintDirtyRegions(RepaintManager.java:693)
   at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:125)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:137)
   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)