java.lang.IllegalArgumentException: view is invalid
   at javax.help.search.MergingSearchEngine.merge(MergingSearchEngine.java:91)
   at org.netbeans.modules.javahelp.JavaHelp.createSearchEngine(JavaHelp.java:197)
   at org.netbeans.modules.javahelp.JavaHelpQuery.createSearchEngine(JavaHelpQuery.java:188)
   at org.netbeans.modules.javahelp.JavaHelpQuery.search(JavaHelpQuery.java:88)
   at org.netbeans.modules.javahelp.JavaHelpQuickSearchProviderImpl.evaluate(JavaHelpQuickSearchProviderImpl.java:70)
   at org.netbeans.modules.quicksearch.CommandEvaluator$1.run(CommandEvaluator.java:207)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1418)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1957)