code: protected void error(String msg, Object[] args)
            throws javax.xml.transform.TransformerException
    {
  
      String fmsg = XSLMessages.createXPATHMessage(msg, args);
  
      // boolean shouldThrow = support.problem(m_support.XPATHPROCESSOR, 
      //                                      m_support.ERROR,
      //                                      null, 
      //                                      null, fmsg, 0, 0);
      // if(shouldThrow)
      {
        throw new XPathException(fmsg, this);
      }
    }
docs: Tell the user of an error, and probably throw an
  exception.
  
  @param msg Error message to issue
  @param args Arguments to use in the message
  
  @throws javax.xml.transform.TransformerException