Check for ErrorRedirect response

var msg = $context.currentItem.previousItem;

try
{
  checkForError(msg);
}
finally
{
  msg.clearResponse();
}

// Checks for error redirect.
// Throws exception if found.
function checkForError(message)
{
  var responseText = message.getResponse(msg.RESPONSE_HTTP_BODY);
  if (responseText != null)
  {
    var errorPrefix = "errorRedirect.htm%3FError%3D";
    var errorTerminator = "%26";
    var errorIndex = responseText.indexOf(errorPrefix);
    if (errorIndex >= 0)
    {
      var errorText = responseText.substring(errorIndex + errorPrefix.length);
      var endIndex = errorText.indexOf(errorTerminator);
      if (endIndex > 0)
        errorText = errorText.substring(0, endIndex);
      var error = 'throw "' + message.name + ': ' + errorText + '"';
      eval(error);
    }
  }
}