java.lang.NullPointerException
   at javax.swing.BufferStrategyPaintManager.flushAccumulatedRegion(BufferStrategyPaintManager.java:399)
   at javax.swing.BufferStrategyPaintManager.copyArea(BufferStrategyPaintManager.java:327)
   at javax.swing.RepaintManager.copyArea(RepaintManager.java:1240)
   at javax.swing.JViewport.blitDoubleBuffered(JViewport.java:1604)
   at javax.swing.JViewport.windowBlitPaint(JViewport.java:1573)
   at javax.swing.JViewport.setViewPosition(JViewport.java:1118)
   at javax.swing.JViewport.scrollRectToVisible(JViewport.java:415)
   at javax.swing.JComponent.scrollRectToVisible(JComponent.java:3065)
   at javax.swing.text.DefaultCaret.adjustVisibility(DefaultCaret.java:266)
   at javax.swing.text.DefaultCaret.repaintNewCaret(DefaultCaret.java:1294)
   at javax.swing.text.DefaultCaret$1.run(DefaultCaret.java:1268)
   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:159)
   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)