java.lang.NullPointerException
   at org.netbeans.lib.lexer.inc.TokenListListUpdate.createJoinTokenListChange(TokenListListUpdate.java:284)
   at org.netbeans.lib.lexer.inc.TokenHierarchyUpdate$UpdateItem.update(TokenHierarchyUpdate.java:327)
   at org.netbeans.lib.lexer.inc.TokenHierarchyUpdate.processLevelInfos(TokenHierarchyUpdate.java:225)
   at org.netbeans.lib.lexer.inc.TokenHierarchyUpdate.updateImpl(TokenHierarchyUpdate.java:196)
   at org.netbeans.lib.lexer.inc.TokenHierarchyUpdate.update(TokenHierarchyUpdate.java:134)
   at org.netbeans.lib.lexer.TokenHierarchyOperation.textModified(TokenHierarchyOperation.java:605)
   at org.netbeans.spi.lexer.TokenHierarchyControl.textModified(TokenHierarchyControl.java:96)
   at org.netbeans.lib.lexer.inc.DocumentInput.textModified(DocumentInput.java:152)
   at org.netbeans.lib.lexer.inc.DocumentInput.removeUpdate(DocumentInput.java:145)
   at org.netbeans.lib.editor.util.swing.PriorityDocumentListenerList.removeUpdate(PriorityDocumentListenerList.java:116)
   at javax.swing.text.AbstractDocument.fireRemoveUpdate(AbstractDocument.java:259)
   at org.netbeans.editor.BaseDocument.fireRemoveUpdate(BaseDocument.java:1660)
   at org.netbeans.editor.BaseDocumentEvent.undo(BaseDocumentEvent.java:287)
   at org.netbeans.editor.GuardedDocumentEvent.undo(GuardedDocumentEvent.java:72)
   at org.netbeans.modules.editor.lib2.document.StableCompoundEdit.undo(StableCompoundEdit.java:93)
   at org.netbeans.editor.BaseDocument$AtomicCompoundEdit.undo(BaseDocument.java:2308)
   at org.netbeans.editor.BaseDocument.undoAtomicEdits(BaseDocument.java:2226)
   at org.netbeans.editor.BaseDocument.breakAtomicLock(BaseDocument.java:1833)
   at org.netbeans.editor.GuardedDocument.runAtomicAsUser(GuardedDocument.java:362)
   at org.netbeans.editor.BaseKit$DefaultKeyTypedAction.actionPerformed(BaseKit.java:1256)
   at org.netbeans.editor.ext.ExtKit$ExtDefaultKeyTypedAction.actionPerformed(ExtKit.java:1080)
   at org.netbeans.editor.BaseAction.actionPerformed(BaseAction.java:339)
   at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1663)
   at javax.swing.JComponent.processKeyBinding(JComponent.java:2882)
   at javax.swing.JComponent.processKeyBindings(JComponent.java:2929)
   at javax.swing.JComponent.processKeyEvent(JComponent.java:2845)
   at java.awt.Component.processEvent(Component.java:6312)
   at java.awt.Container.processEvent(Container.java:2236)
   at java.awt.Component.dispatchEventImpl(Component.java:4891)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
   at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:806)
   at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1074)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:945)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:771)
   at java.awt.Component.dispatchEventImpl(Component.java:4762)
   at java.awt.Container.dispatchEventImpl(Container.java:2294)
   at java.awt.Window.dispatchEventImpl(Window.java:2750)
   at java.awt.Component.dispatchEvent(Component.java:4713)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:709)
   at java.awt.EventQueue$3.run(EventQueue.java:703)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
   at java.awt.EventQueue$4.run(EventQueue.java:731)
   at java.awt.EventQueue$4.run(EventQueue.java:729)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)