BasicValidator.ValidIsotopeExistence problem

[ghost]

BasicValidator.ValidIsotopeExistence smiles with no isotope information e.g. "CC" throws error "Isotope with this mass number is not known for this element." NCDK (and also cdk) code is

                if (isotope.MassNumber != 0)

should be

                if (isotope.MassNumber != null)

test code, call

        validate("CC");
        validate("[13C]C");
        validate("[30C]C");

        private static void validate(string s) {    
            var builder = ChemObjectBuilder.Instance;
            ModelBuilder3D builder3D = ModelBuilder3D.GetInstance(builder);
            IAtomContainer m = builder3D.Generate3DCoordinates(molecule: smilesToMol(s), clone: false);
            var engine  = new ValidatorEngine();
            engine.Add(new BasicValidator());
            engine.Add(new CDKValidator());
            engine.Add(new Geometry3DValidator());
            var report = engine.ValidateMolecule(m);

            for(int i=0;i<report.Errors.Count;i++){
                Console.WriteLine("Valdation errors are: " +report.Errors[i].Error);
            }
        }

    private static IAtomContainer smilesToMol(string s)
    {
        var builder = ChemObjectBuilder.Instance;
        var m = new SmilesParser(builder).ParseSmiles(s);
        m = MoleculeSanityCheck.CheckAndCleanMolecule(m);

        AtomContainerManipulator.ConvertImplicitToExplicitHydrogens(m);
        AtomContainerManipulator.PercieveAtomTypesAndConfigureUnsetProperties(m);
        return m;
    }