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.plaf.basic.BasicScrollPaneUI$Handler.vsbStateChanged(BasicScrollPaneUI.java:1029)
   at javax.swing.plaf.basic.BasicScrollPaneUI$Handler.stateChanged(BasicScrollPaneUI.java:1018)
   at javax.swing.DefaultBoundedRangeModel.fireStateChanged(DefaultBoundedRangeModel.java:348)
   at javax.swing.DefaultBoundedRangeModel.setRangeProperties(DefaultBoundedRangeModel.java:285)
   at javax.swing.DefaultBoundedRangeModel.setValue(DefaultBoundedRangeModel.java:151)
   at javax.swing.JScrollBar.setValue(JScrollBar.java:446)
   at javax.swing.plaf.basic.BasicScrollPaneUI$Handler.mouseWheelMoved(BasicScrollPaneUI.java:964)
   at java.awt.Component.processMouseWheelEvent(Component.java:6378)
   at java.awt.Component.processEvent(Component.java:6062)
   at java.awt.Container.processEvent(Container.java:2039)
   at java.awt.Component.dispatchEventImpl(Component.java:4653)
   at java.awt.Container.dispatchEventToSelf(Container.java:2121)
   at java.awt.Component.dispatchMouseWheelToAncestor(Component.java:4803)
   at java.awt.Component.dispatchEventImpl(Component.java:4539)
   at java.awt.Container.dispatchEventImpl(Container.java:2097)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.LightweightDispatcher.retargetMouseEvent(LightweightDispatcher.java:4575)
   at java.awt.LightweightDispatcher.processMouseEvent(LightweightDispatcher.java:4265)
   at java.awt.LightweightDispatcher.dispatchEvent(LightweightDispatcher.java:4166)
   at java.awt.Container.dispatchEventImpl(Container.java:2083)
   at java.awt.Window.dispatchEventImpl(Window.java:2482)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
   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.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
   at java.awt.EventQueue$2.run(EventQueue.java:621)
   at java.awt.EventQueue$2.run(EventQueue.java:619)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
   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)