title: TypeError: a is null
body: <p>I'm using the following jQuery Ajax call... anyhow it's not working.</p>
  
  <p>Error:<code>TypeError: a is null</code></p>
  
  <p>Here is my Code:</p>
  
  <pre><code>var prefixUrl = "autocomplete?action=complete&amp;id=";
  $('#complete-field').bind('keyup', function(){
  var url =  prefixUrl + escape($('#complete-field').val());
  $.ajax({
      type: "GET",
      getUrl:url,
      dataType: "xml",
      success: function(responseXML) {
          var composers = responseXML.getElementsByTagName("composers")[0];
          if (composers.childNodes.length &gt; 0) {
  
              $('#complete-table').css("border", "1px solid green");
              $('#complete-table').css("margin", "128px 0 0 -82px");
  
              for (var loop = 0; loop &lt; composers.childNodes.length; loop++) {
                  var composer = composers.childNodes[loop];
                  var firstName = composer.getElementsByTagName("firstName")[0];
                  var lastName = composer.getElementsByTagName("lastName")[0];
                  var composerId = composer.getElementsByTagName("id")[0];
  
                  appendComposer(firstName.childNodes[0].nodeValue, lastName.childNodes[0].nodeValue, composerId.childNodes[0].nodeValue);
              }
          }
      },
      error:function (xhr, ajaxOptions, thrownError) {
          alert('xhr.status: ' + xhr.status);
          alert(thrownError);
      }
    });
  });
  </code></pre>
  
  <p>Any Idea please?</p>
  
  <p>Many Thanks</p>