java.lang.NullPointerException
   at org.netbeans.modules.editor.hints.AnnotationHolder.insertUpdate(AnnotationHolder.java:312)
   at org.netbeans.lib.editor.util.swing.PriorityDocumentListenerList.insertUpdate(PriorityDocumentListenerList.java:79)
   at javax.swing.text.AbstractDocument.fireInsertUpdate(AbstractDocument.java:0)
   at org.netbeans.editor.BaseDocument.fireInsertUpdate(BaseDocument.java:1631)
   at org.netbeans.editor.BaseDocumentEvent.undo(BaseDocumentEvent.java:289)
   at org.netbeans.editor.GuardedDocumentEvent.undo(GuardedDocumentEvent.java:69)
   at javax.swing.undo.CompoundEdit.undo(CompoundEdit.java:0)
   at org.netbeans.editor.BaseDocument$AtomicCompoundEdit.undo(BaseDocument.java:2164)
   at org.netbeans.editor.BaseDocument.breakAtomicLock(BaseDocument.java:1828)
   at org.netbeans.editor.GuardedDocument.runAtomicAsUser(GuardedDocument.java:347)
   at org.netbeans.editor.ActionFactory$RemoveLineAction.actionPerformed(ActionFactory.java:353)
   at org.netbeans.editor.BaseAction.actionPerformed(BaseAction.java:336)
   at org.openide.awt.AlwaysEnabledAction$1.run(AlwaysEnabledAction.java:137)
   at org.openide.util.actions.ActionInvoker$1.run(ActionInvoker.java:92)
   at org.openide.util.actions.ActionInvoker.doPerformAction(ActionInvoker.java:113)
   at org.openide.util.actions.ActionInvoker.invokeAction(ActionInvoker.java:96)
   at org.openide.awt.AlwaysEnabledAction.actionPerformed(AlwaysEnabledAction.java:140)
   at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:0)
   at javax.swing.JComponent.processKeyBinding(JComponent.java:0)
   at javax.swing.JComponent.processKeyBindings(JComponent.java:0)
   at javax.swing.JComponent.processKeyEvent(JComponent.java:0)
   at java.awt.Component.processEvent(Component.java:0)
   at java.awt.Container.processEvent(Container.java:0)
   at java.awt.Component.dispatchEventImpl(Component.java:0)
   at java.awt.Container.dispatchEventImpl(Container.java:0)
   at java.awt.Component.dispatchEvent(Component.java:0)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:0)
   at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:0)
   at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:0)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:0)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:0)
   at java.awt.Component.dispatchEventImpl(Component.java:0)
   at java.awt.Container.dispatchEventImpl(Container.java:0)
   at java.awt.Window.dispatchEventImpl(Window.java:0)
   at java.awt.Component.dispatchEvent(Component.java:0)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:0)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:133)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:0)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:0)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:0)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:0)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:0)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:0)