java.lang.NullPointerException
   at org.netbeans.modules.editor.hints.AnnotationHolder.insertUpdate(AnnotationHolder.java:329)
   at org.netbeans.lib.editor.util.swing.PriorityDocumentListenerList.insertUpdate(PriorityDocumentListenerList.java:85)
   at javax.swing.text.AbstractDocument.fireInsertUpdate(AbstractDocument.java:185)
   at org.netbeans.editor.BaseDocument.fireInsertUpdate(BaseDocument.java:1670)
   at org.netbeans.editor.BaseDocumentEvent.undo(BaseDocumentEvent.java:293)
   at org.netbeans.editor.GuardedDocumentEvent.undo(GuardedDocumentEvent.java:72)
   at javax.swing.undo.CompoundEdit.undo(CompoundEdit.java:46)
   at org.netbeans.editor.BaseDocument$AtomicCompoundEdit.undo(BaseDocument.java:2223)
   at org.netbeans.editor.BaseDocument.breakAtomicLock(BaseDocument.java:1874)
   at org.netbeans.editor.GuardedDocument.runAtomicAsUser(GuardedDocument.java:350)
   at org.netbeans.editor.BaseKit$DeleteCharAction.actionPerformed(BaseKit.java:1753)
   at org.netbeans.modules.editor.java.JavaKit$JavaDeleteCharAction.actionPerformed(JavaKit.java:741)
   at org.netbeans.editor.BaseAction.actionPerformed(BaseAction.java:339)
   at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1639)
   at javax.swing.JComponent.processKeyBinding(JComponent.java:2851)
   at javax.swing.JComponent.processKeyBindings(JComponent.java:2886)
   at javax.swing.JComponent.processKeyEvent(JComponent.java:2814)
   at java.awt.Component.processEvent(Component.java:6065)
   at java.awt.Container.processEvent(Container.java:2041)
   at java.awt.Component.dispatchEventImpl(Component.java:4651)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1850)
   at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:712)
   at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:990)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:855)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:676)
   at java.awt.Component.dispatchEventImpl(Component.java:4523)
   at java.awt.Container.dispatchEventImpl(Container.java:2099)
   at java.awt.Window.dispatchEventImpl(Window.java:2478)
   at java.awt.Component.dispatchEvent(Component.java:4481)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:643)
   at java.awt.EventQueue.access$000(EventQueue.java:84)
   at java.awt.EventQueue$1.run(EventQueue.java:602)
   at java.awt.EventQueue$1.run(EventQueue.java:600)
   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:616)
   at java.awt.EventQueue$2.run(EventQueue.java:614)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:613)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:148)
   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)