java.lang.IllegalArgumentException: view is invalid
   at javax.help.search.MergingSearchEngine.merge(MergingSearchEngine.java:91)
   at javax.help.JHelpSearchNavigator.merge(JHelpSearchNavigator.java:168)
   at javax.help.plaf.basic.BasicSearchNavigatorUI.addSubHelpSets(BasicSearchNavigatorUI.java:275)
   at javax.help.plaf.basic.BasicSearchNavigatorUI.reloadData(BasicSearchNavigatorUI.java:225)
   at javax.help.plaf.basic.BasicSearchNavigatorUI.installUI(BasicSearchNavigatorUI.java:174)
   at javax.swing.JComponent.setUI(JComponent.java:666)
   at javax.help.JHelpNavigator.setUI(JHelpNavigator.java:257)
   at javax.help.JHelpNavigator.updateUI(JHelpNavigator.java:276)
   at javax.help.JHelpNavigator.<init>(JHelpNavigator.java:105)
   at javax.help.JHelpSearchNavigator.<init>(JHelpSearchNavigator.java:66)
   at javax.help.SearchView.createNavigator(SearchView.java:80)
   at javax.help.JHelp.setupNavigators(JHelp.java:149)
   at javax.help.JHelp.<init>(JHelp.java:126)
   at javax.help.JHelp.<init>(JHelp.java:76)
   at org.netbeans.modules.javahelp.JavaHelp.createJHelp(JavaHelp.java:0)
   at org.netbeans.modules.javahelp.JavaHelp.createAndDisplayJHelp(JavaHelp.java:0)
   at org.netbeans.modules.javahelp.JavaHelp.showHelp(JavaHelp.java:0)
   at org.netbeans.modules.javahelp.JavaHelpQuickSearchProviderImpl$1.run(JavaHelpQuickSearchProviderImpl.java:0)
   at org.netbeans.modules.quicksearch.QuickSearchPopup.invoke(QuickSearchPopup.java:0)
   at org.netbeans.modules.quicksearch.AbstractQuickSearchComboBar$6.run(AbstractQuickSearchComboBar.java:0)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
   at java.awt.EventQueue.access$500(EventQueue.java:97)
   at java.awt.EventQueue$3.run(EventQueue.java:709)
   at java.awt.EventQueue$3.run(EventQueue.java:703)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:0)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)