java.lang.ClassCastException: org.netbeans.modules.css.gsf.api.CssParserResult cannot be cast to org.netbeans.modules.html.editor.gsf.HtmlParserResult
        at org.netbeans.modules.html.editor.gsf.HtmlStructureScanner.folds(HtmlStructureScanner.java:118)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.addTree(GsfFoldManager.java:493)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.scan(GsfFoldManager.java:489)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.access$100(GsfFoldManager.java:298)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask$1.run(GsfFoldManager.java:395)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask$1.run(GsfFoldManager.java:402)
        at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:131)
        at org.netbeans.modules.parsing.api.ParserManager$UserTaskAction.run(ParserManager.java:115)
Caused: org.netbeans.modules.parsing.spi.ParseException
        at org.netbeans.modules.parsing.impl.TaskProcessor.runUserTask(TaskProcessor.java:190)
        at org.netbeans.modules.parsing.api.ParserManager.parse(ParserManager.java:101)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.gsfFoldScan(GsfFoldManager.java:377)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.run(GsfFoldManager.java:353)
        at org.netbeans.modules.csl.editor.fold.GsfFoldManager$JavaElementFoldTask.run(GsfFoldManager.java:298)
        at org.netbeans.modules.parsing.impl.TaskProcessor$CompilationJob.run(TaskProcessor.java:681)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:619)