Attached invalid schematas lead to NPE if ErrorHandler is set.

The parseSchemaDoc method which fails with NPE:
-------Code snippet--------------
class TestRun {
   
    protected static class ErrorHandler extends DefaultHandler {
    public int warningCounter = 0;
    public int errorCounter = 0;
    protected final PrintWriter err;

    public ErrorHandler(PrintWriter err) {
      this.err = err;
    }

    public void warning(SAXParseException e) throws SAXException {
      warningCounter++;
      err.println("Warning: " + strException(e));
      err.flush();
    }

    public void error(SAXParseException e) throws SAXException {
      errorCounter++;
      err.println("Error: " + strException(e));
      err.flush();
    }

    public void fatalError(SAXParseException e) throws SAXException {
      err.println("Fatal Error: " + strException(e));
      err.flush();
      throw e;
    }
  }
  
  static public Status parseSchemaDoc(StreamSource sources) {
    SchemaFactory schemaFactory =
            SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");
    
    ErrorHandler errorHandler = new ErrorHandler(new PrintWriter(System.out)); //!!
    
    schemaFactory.setErrorHandler(errorHandler);
   
    try {
        schemaFactory.newSchema(sources); //!!
    } catch (SAXException e) {
        String msg = "Fatal Error: " + strException(e);
        e.printStackTrace();
        return Status.failed(msg);
    }

    if (errorHandler.errorCounter != 0) {
        return Status.failed(errorHandler.errorCounter + " errors, "
                + errorHandler.warningCounter + " warnings.");
    }
    return Status.passed("OK.");
  }
  
  protected static String strException(Exception ex) {
        StringBuffer sb = new StringBuffer();

        while (ex != null) {
            if (ex instanceof SAXParseException) {
                SAXParseException e = (SAXParseException) ex;
                sb.append("" + e.getSystemId() + "(" + e.getLineNumber() + ","
                        + e.getColumnNumber() + "): " + e.getMessage());
                ex = e.getException();
            } else {
                sb.append(ex);
                ex = null;
            }
        }
        return sb.toString();
    }

...............
}
-----End of code snippet----------------
The stack trace is as follows:

Error: file:/files/devel/ws/jck/7/_build/out/runtime/shared/suite/JCK-runtime-7/tests/xml_schema/msData/notations/notatF037.xsd(5,71): s4s-elt-invalid: Element 'notation' is not a valid element in a schema document.
Error: file:/files/devel/ws/jck/7/_build/out/runtime/shared/suite/JCK-runtime-7/tests/xml_schema/msData/notations/notatF037.xsd(5,71): s4s-elt-must-match.1: The content of 'identity constraint' must match (annotation?, selector, field+). A problem was found starting at: selector.
Exception in thread "main" java.lang.NullPointerException
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDAbstractIDConstraintTraverser.traverseIdentityConstraint(XSDAbstractIDConstraintTraverser.java:107)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDUniqueOrKeyTraverser.traverse(XSDUniqueOrKeyTraverser.java:74)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseNamedElement(XSDElementTraverser.java:401)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseGlobal(XSDElementTraverser.java:217)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.traverseSchemas(XSDHandler.java:1262)
at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.parseSchema(XSDHandler.java:583)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadSchema(XMLSchemaLoader.java:555)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:522)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:488)
at com.sun.org.apache.xerces.internal.jaxp.validation.XMLSchemaFactory.newSchema(XMLSchemaFactory.java:214)
at javasoft.sqe.tests.api.xml.schema.TestRun.parseSchemaDoc(TestRun.java:316)
at javasoft.sqe.tests.api.xml.schema.TestRun.runPositiveTest(TestRun.java:251)
at javasoft.sqe.tests.api.xml.schema.TestRun.runNegativeTest(TestRun.java:329)
at javasoft.sqe.tests.api.xml.schema.TestRun.run(TestRun.java:119)
at javasoft.sqe.tests.api.xml.schema.TestRun.setLogsAndRun(TestRun.java:342)
at javasoft.sqe.tests.api.xml.schema.TestRun.main(TestRun.java:350)

Also the same NPE can be shown if the standard JDK tool xjc is used

> xjc notatF071.xsd
parsing a schema...
[ERROR] s4s-elt-invalid: Element 'notation' is not a valid element in a schema document.
  line 5 of file:/files/devel/analysis/notatF071.xsd

[ERROR] s4s-elt-must-match.1: The content of 'identity constraint' must match (annotation?, selector, field+). A problem was found starting at: selector.
  line 5 of file:/files/devel/analysis/notatF071.xsd

Exception in thread "main" java.lang.NullPointerException
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDAbstractIDConstraintTraverser.traverseIdentityConstraint(XSDAbstractIDConstraintTraverser.java:104)
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDUniqueOrKeyTraverser.traverse(XSDUniqueOrKeyTraverser.java:71)
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseNamedElement(XSDElementTraverser.java:398)
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDElementTraverser.traverseGlobal(XSDElementTraverser.java:214)
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.traverseSchemas(XSDHandler.java:1258)
        at com.sun.org.apache.xerces.internal.impl.xs.traversers.XSDHandler.parseSchema(XSDHandler.java:579)
        at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadSchema(XMLSchemaLoader.java:552)
        at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:519)
        at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaLoader.loadGrammar(XMLSchemaLoader.java:485)
        at com.sun.org.apache.xerces.internal.jaxp.validation.XMLSchemaFactory.newSchema(XMLSchemaFactory.java:210)
        at com.sun.tools.internal.xjc.reader.xmlschema.parser.SchemaConstraintChecker.check(SchemaConstraintChecker.java:90)
        at com.sun.tools.internal.xjc.ModelLoader.loadXMLSchema(ModelLoader.java:346)
        at com.sun.tools.internal.xjc.ModelLoader.load(ModelLoader.java:156)
        at com.sun.tools.internal.xjc.ModelLoader.load(ModelLoader.java:102)
        at com.sun.tools.internal.xjc.Driver.run(Driver.java:302)
        at com.sun.tools.internal.xjc.Driver.run(Driver.java:180)
        at com.sun.tools.internal.xjc.Driver._main(Driver.java:105)
        at com.sun.tools.internal.xjc.Driver.access$000(Driver.java:63)
        at com.sun.tools.internal.xjc.Driver$1.run(Driver.java:85)