java.lang.AssertionError: Highlight attributes must not be null.
        at org.netbeans.spi.editor.highlighting.support.OffsetsBag.addHighlightImpl(OffsetsBag.java:453)
        at org.netbeans.spi.editor.highlighting.support.OffsetsBag.addHighlight(OffsetsBag.java:137)
        at org.netbeans.modules.languages.features.SemanticHighlightsLayer$Listener.evaluate(SemanticHighlightsLayer.java:140)
        at org.netbeans.modules.languages.FeatureList.evaluate(FeatureList.java:143)
        at org.netbeans.modules.languages.Language.evaluate(Language.java:365)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:238)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:248)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:248)
        at org.netbeans.modules.languages.ParserManagerImpl.setChange(ParserManagerImpl.java:207)
        at org.netbeans.modules.languages.ParserManagerImpl.parseAST(ParserManagerImpl.java:292)
        at org.netbeans.modules.languages.ParserManagerImpl.access$100(ParserManagerImpl.java:62)
        at org.netbeans.modules.languages.ParserManagerImpl$1.run(ParserManagerImpl.java:166)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)