java.lang.NullPointerException
        at org.netbeans.modules.editor.NbEditorDocument.createEditor(NbEditorDocument.java:170)
        at org.openide.text.CloneableEditor$DoInitialize.initCustomEditor(CloneableEditor.java:352)
        at org.openide.text.CloneableEditor$DoInitialize.initVisual(CloneableEditor.java:454)
        at org.openide.text.CloneableEditor$DoInitialize.run(CloneableEditor.java:255)
        at org.netbeans.core.windows.WindowManagerImpl$Exclusive.run(WindowManagerImpl.java:1302)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:104)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)