java.lang.NullPointerException
        at org.netbeans.modules.editor.NbEditorDocument.createEditor(NbEditorDocument.java:170)
        at org.openide.text.CloneableEditor$DoInitialize.initCustomEditor(CloneableEditor.java:497)
        at org.openide.text.CloneableEditor$DoInitialize.initVisual(CloneableEditor.java:599)
        at org.openide.text.CloneableEditor.getEditorPane(CloneableEditor.java:1067)
        at org.netbeans.modules.java.hints.infrastructure.HintAction.getCurrentFile(HintAction.java:112)
        at org.netbeans.modules.java.hints.infrastructure.HintAction.updateEnabled(HintAction.java:69)
        at org.netbeans.modules.java.hints.infrastructure.HintAction.propertyChange(HintAction.java:145)
        at org.openide.util.WeakListenerImpl$PropertyChange.propertyChange(WeakListenerImpl.java:188)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
        at org.netbeans.core.windows.RegistryImpl.doFirePropertyChange(RegistryImpl.java:318)
        at org.netbeans.core.windows.RegistryImpl.access$100(RegistryImpl.java:66)
        at org.netbeans.core.windows.RegistryImpl$1.run(RegistryImpl.java:170)
        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:117)
        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)