Undefined Offset

I got a similar message. However, after I configured the module, specifically setting some "Allowed Roles" with the modules configuration page, this problem seemed to disappear.

So because it defaults to an array() in
$allowed_roles = variable_get('nodeaccess-roles', array());
the line
if (is_array($roles)) {
always returns true, so I just changed line 577 from
if ($allowed_roles[$key]) {
to
if (array_key_exists($key, $allowed_roles)) {
The problem goes away because once you have defined something your now longer loading the default empty array. I'm not really sure if this is the "proper solution" or has all the behavior desired but it made the error message go away for me so I'm going with it.

-Tristan

Just for information !

I have the following:
Notice : Undefined offset: 1 dans nodeaccess_grants_form() (ligne 577 dans /homepages/42/d141549472/htdocs/mbc/drupal-7.4/sites/all/modules/nodeaccess/nodeaccess.module).
Notice : Undefined offset: 3 dans nodeaccess_grants_form() (ligne 577 dans /homepages/42/d141549472/htdocs/mbc/drupal-7.4/sites/all/modules/nodeaccess/nodeaccess.module).
Notice : Undefined offset: 2 dans nodeaccess_grants_form() (ligne 577 dans /homepages/42/d141549472/htdocs/mbc/drupal-7.4/sites/all/modules/nodeaccess/nodeaccess.module).

same as patch (with isset instead of array_key_exists as it is faster and more common used in drupal)

function nodeaccess_grants_form($form, &$form_state, $node) {
   if (is_array($roles)) {
     $form['rid'] = array('#tree' => TRUE);
     foreach ($roles as $key => $field) {
-      if ($allowed_roles[$key]) {
+      if (isset($allowed_roles[$key]) && $allowed_roles[$key]) {
         $form['rid'][$key]['name'] = array(
           '#type' => 'hidden',
           '#value' => $field['name'],

Thank you, will push the patch later today to dev version.

Fix pushed to dev.