java.lang.ClassCastException: java.desktop/javax.swing.text.AbstractDocument$DefaultDocumentEventUndoableWrapper cannot be cast to java.desktop/javax.swing.text.AbstractDocument$DefaultDocumentEvent
   at org.netbeans.modules.bugtracking.commons.UndoRedoSupport$CompoundUndoManager.undoableEditHappened(UndoRedoSupport.java:161)
   at javax.swing.text.AbstractDocument.fireUndoableEditUpdate(AbstractDocument.java:293)
   at javax.swing.text.AbstractDocument.handleRemove(AbstractDocument.java:632)
   at javax.swing.text.AbstractDocument.remove(AbstractDocument.java:596)
   at javax.swing.text.DefaultEditorKit$DeleteNextCharAction.actionPerformed(DefaultEditorKit.java:1112)
   at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1805)
   at javax.swing.JComponent.processKeyBinding(JComponent.java:2901)
   at javax.swing.JComponent.processKeyBindings(JComponent.java:2949)
   at javax.swing.JComponent.processKeyEvent(JComponent.java:2863)
   at java.awt.Component.processEvent(Component.java:6354)
   at java.awt.Container.processEvent(Container.java:2259)
   at java.awt.Component.dispatchEventImpl(Component.java:4960)
   at java.awt.Container.dispatchEventImpl(Container.java:2317)
   at java.awt.Component.dispatchEvent(Component.java:4792)
   at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1950)
   at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:827)
   at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1096)
   at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:966)
   at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:792)
   at java.awt.Component.dispatchEventImpl(Component.java:4841)
   at java.awt.Container.dispatchEventImpl(Container.java:2317)
   at java.awt.Window.dispatchEventImpl(Window.java:2758)
   at java.awt.Component.dispatchEvent(Component.java:4792)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:761)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:712)
   at java.awt.EventQueue$3.run(EventQueue.java:706)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:88)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:98)
   at java.awt.EventQueue$4.run(EventQueue.java:734)
   at java.awt.EventQueue$4.run(EventQueue.java:732)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:88)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:731)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:199)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)