java.lang.AssertionError: Highlight attributes must not be null.
        at org.netbeans.spi.editor.highlighting.support.OffsetsBag.addHighlightImpl(OffsetsBag.java:475)
        at org.netbeans.spi.editor.highlighting.support.OffsetsBag.addHighlight(OffsetsBag.java:159)
        at org.netbeans.modules.languages.features.SemanticHighlightsLayer$Listener.evaluate(SemanticHighlightsLayer.java:151)
        at org.netbeans.modules.languages.FeatureList.evaluate(FeatureList.java:167)
        at org.netbeans.modules.languages.Language.evaluate(Language.java:387)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:260)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:270)
        at org.netbeans.modules.languages.ParserManagerImpl.evaluate(ParserManagerImpl.java:270)
        at org.netbeans.modules.languages.ParserManagerImpl.setChange(ParserManagerImpl.java:229)
        at org.netbeans.modules.languages.ParserManagerImpl.parseAST(ParserManagerImpl.java:314)
        at org.netbeans.modules.languages.ParserManagerImpl.access$100(ParserManagerImpl.java:84)
        at org.netbeans.modules.languages.ParserManagerImpl$1.run(ParserManagerImpl.java:188)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:561)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:986)