NPE TermColorKeywordImpl.toString

[dmercuriali]

Got an error in production on TermColorKeywordImpl.toString

Caused by: java.lang.NullPointerException
at cz.vutbr.web.csskit.TermColorKeywordImpl.toString(TermColorKeywordImpl.java:36)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitValuepart(CSSParserVisitorImpl.java:996)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitTermValuePart(CSSParserVisitorImpl.java:854)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitTerms(CSSParserVisitorImpl.java:821)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitDeclaration(CSSParserVisitorImpl.java:730)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitDeclarations(CSSParserVisitorImpl.java:691)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitRuleset(CSSParserVisitorImpl.java:668)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitStatement(CSSParserVisitorImpl.java:282)
at cz.vutbr.web.csskit.antlr4.CSSParserVisitorImpl.visitStylesheet(CSSParserVisitorImpl.java:241)
at cz.vutbr.web.csskit.antlr4.CSSParserFactory.parse(CSSParserFactory.java:206)
at cz.vutbr.web.csskit.antlr4.CSSParserFactory.parseAndImport(CSSParserFactory.java:147)
at cz.vutbr.web.csskit.antlr4.CSSParserFactory.parse(CSSParserFactory.java:72)
at cz.vutbr.web.csskit.antlr4.CSSParserFactory.parse(CSSParserFactory.java:93)
at cz.vutbr.web.css.CSSFactory.parseString(CSSFactory.java:546)
at cz.vutbr.web.css.CSSFactory.parseString(CSSFactory.java:521)

We are still on version 3.2, but the interested code looks the same (the code at CSSParserVisitorImpl.java:996 was moved in a new method CSSParserVisitorImpl#findSpecificType but the code is actually the same).

We couldn't reproduce the error and it seems that TermColorKeywordImpl#keyword should never be null.

I'll submit a pull request adding some ifs around debug statements. This won't solve the root problem but will avoid a crash on a debug statement (and avoid some string allocation).

[dmercuriali]

Pull request #101

[radkovo]

The problem seems to be somewhere in the parser code (e.g. CSSParserVisitorImpl). The parser implementation has changed significantly in the last release. I suggest the following approach (which should be always used when reporting a bug in any project):

• First, verify whether the bug is still present in the latest release (jStyleParser 3.3).
• If yes, try to reproduce the bug: in this case, try to find the CSS code that causes the NPE.
• Then, report the issue with the related information attached and/or create a PR that fixes the bug in its origin.

Many thanks!