Code change required: PHP Warning = "Undefined index: drupal_uid in .....xcache_cachepage.inc, line 221"

line 221 of xcache_cachepage.inc requires a correction:

Line 221# original code:
if (empty($_POST) && !$_COOKIE['drupal_uid']) {

Change to:
if (empty($_POST) && empty($_COOKIE['drupal_uid'])) {