java.lang.IllegalStateException
        at org.openide.text.CloneableEditorSupport.prepareDocument(CloneableEditorSupport.java:595)
        at org.openide.text.CloneableEditor$DoInitialize.initNonVisual(CloneableEditor.java:377)
        at org.openide.text.CloneableEditor$DoInitialize.run(CloneableEditor.java:320)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:602)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1084)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.IllegalStateException
        at org.openide.util.RequestProcessor$Task.schedule(RequestProcessor.java:655)
        at org.openide.text.CloneableEditor$DoInitialize.<init>(CloneableEditor.java:287)
        at org.openide.text.CloneableEditor.initialize(CloneableEditor.java:222)
        at org.openide.text.CloneableEditor.componentShowing(CloneableEditor.java:198)
        at org.openide.windows.WindowManager.componentShowing(WindowManager.java:332)
        at org.netbeans.core.windows.WindowManagerImpl.componentShowing(WindowManagerImpl.java:1022)
        at org.netbeans.core.windows.view.DefaultView.changeGUI(DefaultView.java:161)
        at org.netbeans.core.windows.ViewRequestor.dispatchRequest(ViewRequestor.java:269)
        at org.netbeans.core.windows.ViewRequestor.processRequest(ViewRequestor.java:245)
        at org.netbeans.core.windows.ViewRequestor.postRequest(ViewRequestor.java:183)
        at org.netbeans.core.windows.ViewRequestor.scheduleRequest(ViewRequestor.java:123)
        at org.netbeans.core.windows.Central.activateModeTopComponent(Central.java:1760)
        at org.netbeans.core.windows.WindowManagerImpl.topComponentRequestActive(WindowManagerImpl.java:1145)
        at org.openide.windows.TopComponent.requestActive(TopComponent.java:789)
        at org.openide.windows.CloneableOpenSupport$1.run(CloneableOpenSupport.java:99)
        at org.openide.util.Mutex.doEvent(Mutex.java:1335)
        at org.openide.util.Mutex.writeAccess(Mutex.java:452)
        at org.openide.windows.CloneableOpenSupport.open(CloneableOpenSupport.java:95)
        at org.openide.text.CloneableEditorSupport.open(CloneableEditorSupport.java:463)
        at org.openide.windows.CloneableOpenSupport.edit(CloneableOpenSupport.java:118)
        at org.netbeans.modules.project.ui.ProjectUtilities$1.open(ProjectUtilities.java:110)
        at org.netbeans.modules.project.ui.ProjectUtilities.openProjectFiles(ProjectUtilities.java:515)
        at org.netbeans.modules.project.ui.OpenProjectList$8.run(OpenProjectList.java:1125)
        at org.netbeans.modules.project.ui.OpenProjectList$8.run(OpenProjectList.java:1122)
        at org.openide.util.Mutex$1AWTWorker.run(Mutex.java:1370)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:125)
        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)