User manager error

<?php
$membersFolderId = 12;
$ancestors = $modx->getParentIds( (integer) $resource->get('id'));

if( in_array($membersFolderId, $ancestors)) {
    $username = $user->get('username'); // might need to be $modx->user
    $resource->joinGroup($userName);
}

$membersFolderId = 14;
$ancestors = $modx->getParentIds( $resource->get('id'));
 
if( in_array($membersFolderId, $ancestors)) {
    $username = $user->get('username'); // might need to be $modx->user
    $resource->joinGroup($userName);
}

<?php
/* @var $resource modResource */
/* @var $modx modX */
/* @var $mode int */

$membersFolderId = 12;

/* If there are users that already have resources, 
   comment out the following line and the plugin will
   work for them when they edit their existing 
   resources. Once all the Users and Resources
   are in their groups, you can uncomment it 
   to make things a little faster */

if ($mode != modSystemEvent::MODE_NEW) return;

function getAncestors($id, &$ancestors) {
    /* @var $p modResource */
    global $modx;
    if (!empty($id)) {
        $p = $modx->getObject('modResource', $id);
        if ($p) {
            $parentId = $p->get('parent');
            $ancestors[] = $id;
            getAncestors($parentId, $ancestors);
        }
        else {
            $ancestors[] = 'failed to get parent';
        }
    }
    return;
}

$docId = (integer)$resource->get('id');
$ancestors = array();

$userName = $modx->user->get('username');
$docId = $resource->get('parent');
getAncestors($docId, $ancestors);
if (!in_array($docId, $ancestors)) {
    return '';
}

$group = $modx->getObject('modResourceGroup', array('name' => $userName));

/* create resource group if it doesn't exist */
if (empty($group)) {
    /* @var $group modUserGroup */
    $group = $modx->newObject('modResourceGroup');
    if ($group) {
        $group->set('name', $userName);
        $group->save();
    }
}
/* add Resource to Resource Group */
$resource->joinGroup($userName);


$group = $modx->getObject('modUserGroup', array('name' => $userName));

/* create user's user group if it doesn't exist */
if (empty($group)) {
    $group = $modx->newObject('modUserGroup');
    if ($group) {
        $group->set('name', $userName);
        $group->save();
    }
}
/* Add user to group if not already a member */
if (!$modx->user->isMember($userName)) {
    $modx->user->joinGroup($userName);
}
$group = $modx->getObject('modUserGroup', array(
                                               'name' => 'AllMembers'));

return '';