title: 'object reference not set to an instance of an object' for HTMLWorker parser
body: <pre><code>Document document = new Document(PageSize.LETTER, 10, 10, 10, 10);
  StringReader reader = new StringReader(edittedHTML);
  HTMLWorker worker = new HTMLWorker(document);
  string fileName = "test.pdf";
  PdfWriter.GetInstance(document, new FileStream(fileName, FileMode.Create));
  document.Open();
  worker.Parse(reader);
  worker.EndDocument();
  worker.Close();
  document.Close();
  </code></pre>
  
  <p>When the program runs to worker.Parse, it throws out an error just like the title said.</p>
  
  <p>The edtted HTML is the HTML string of an HTML page.</p>
  
  <p>Anyone know how to solve this, or what is going wrong?</p>
  
  <p>The stack trace:</p>
  
  <pre>
  at iTextSharp.text.html.simpleparser.HTMLWorker.StartElement(String tag, IDictionary`2 attrs)
  at iTextSharp.text.xml.simpleparser.SimpleXMLParser.ProcessTag(Boolean start)
  at iTextSharp.text.xml.simpleparser.SimpleXMLParser.Go(TextReader reader)
  at iTextSharp.text.xml.simpleparser.SimpleXMLParser.Parse(ISimpleXMLDocHandler doc, ISimpleXMLDocHandlerComment comment, TextReader r, Boolean html)
  at iTextSharp.text.html.simpleparser.HTMLWorker.Parse(TextReader reader)
  at TestPdfApplication.Form1.button1_Click(Object sender, EventArgs e) in C:\Users\TLiu\Documents\Visual Studio 2010\Projects\TestPdfApplication\TestPdfApplication\Form1.cs:line 68
  </pre>