java.lang.NullPointerException
   at javax.swing.BoxLayout.preferredLayoutSize(BoxLayout.java:282)
   at javax.swing.plaf.basic.DefaultMenuLayout.preferredLayoutSize(DefaultMenuLayout.java:49)
   at java.awt.Container.preferredSize(Container.java:1581)
   at java.awt.Container.getPreferredSize(Container.java:1566)
   at javax.swing.JComponent.getPreferredSize(JComponent.java:1634)
   at javax.swing.JRootPane$RootLayout.layoutContainer(JRootPane.java:989)
   at java.awt.Container.layout(Container.java:1398)
   at java.awt.Container.doLayout(Container.java:1387)
   at java.awt.Container.validateTree(Container.java:1485)
   at java.awt.Container.validateTree(Container.java:1491)
   at java.awt.Container.validate(Container.java:1457)
   at java.awt.Window.dispatchEventImpl(Window.java:2456)
   at java.awt.Component.dispatchEvent(Component.java:4331)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
   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)