java.lang.AssertionError: Unregister asymmetrically called
   at org.openide.explorer.view.ViewTooltips.unregister(ViewTooltips.java:130)
   at org.openide.explorer.view.TreeView$ExplorerTree.removeNotify(TreeView.java:1801)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at org.openide.explorer.view.TreeView.removeNotify(TreeView.java:678)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at org.netbeans.swing.tabcontrol.TabbedContainer.removeNotify(TabbedContainer.java:943)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.removeNotify(Container.java:2609)
   at javax.swing.JComponent.removeNotify(JComponent.java:4701)
   at java.awt.Container.remove(Container.java:1140)
   at java.awt.Container.remove(Container.java:1198)
   at org.netbeans.core.windows.view.ui.DesktopImpl.setViewComponent(DesktopImpl.java:154)
   at org.netbeans.core.windows.view.ui.DesktopImpl.setSplitRoot(DesktopImpl.java:134)
   at org.netbeans.core.windows.view.ViewHierarchy.setSplitRootIntoDesktop(ViewHierarchy.java:628)
   at org.netbeans.core.windows.view.ViewHierarchy.releaseAll(ViewHierarchy.java:544)
   at org.netbeans.core.windows.view.DefaultView.hideWindowSystem(DefaultView.java:608)
   at org.netbeans.core.windows.view.DefaultView.windowSystemVisibilityChanged(DefaultView.java:500)
   at org.netbeans.core.windows.view.DefaultView.changeGUI(DefaultView.java:180)
   at org.netbeans.core.windows.ViewRequestor.dispatchRequest(ViewRequestor.java:269)
   at org.netbeans.core.windows.ViewRequestor.processVisibilityRequest(ViewRequestor.java:258)
   at org.netbeans.core.windows.ViewRequestor.postVisibilityRequest(ViewRequestor.java:195)
   at org.netbeans.core.windows.ViewRequestor.scheduleRequest(ViewRequestor.java:117)
   at org.netbeans.core.windows.Central.setVisible(Central.java:119)
   at org.netbeans.core.windows.WindowManagerImpl.setVisible(WindowManagerImpl.java:785)
   at org.netbeans.core.windows.WindowSystemImpl.hide(WindowSystemImpl.java:89)
   at org.netbeans.core.NbLifecycleManager$ExitActions.run(NbLifecycleManager.java:127)
   at org.netbeans.ModuleManager.shutDown(ModuleManager.java:1590)
   at org.netbeans.core.startup.ModuleSystem.shutDown(ModuleSystem.java:298)
   at org.netbeans.core.NbLifecycleManager.doExit(NbLifecycleManager.java:164)
   at org.netbeans.core.NbLifecycleManager.access$000(NbLifecycleManager.java:72)
   at org.netbeans.core.NbLifecycleManager$ExitActions.run(NbLifecycleManager.java:120)
   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:130)
   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)