Answered "Code: 200 OK" & "Access denied." Errors While Developing A New Addon.

/* handle request */
$path = $modx->getOption('processorsPath',$modx->mp->config,$corePath.'processors/');
$modx->request->handleRequest(array(
    'processors_path' => $path,
    'location' => '',
));

MP.grid.Entities = function(config) {
    config = config || {};
    Ext.applyIf(config,{
        id: 'mp-grid-entities'
        ,url: MP.config.connectorUrl
        ,baseParams: { action: 'mgr/entities/getlist' }
        ,fields: ['entity_id','menu']
        ,paging: true
        ,remoteSort: true
        ,anchor: '97%'
        ,columns: []
        ,tbar:[]
    });
    MP.grid.Entities.superclass.constructor.call(this,config)
};
Ext.extend(MP.grid.Entities,MODx.grid.Grid);
Ext.reg('mp-grid-entities',MP.grid.Entities);

$start= $modx->getOption('start', $scriptProperties, 0);
$limit= $modx->getOption('limit', $scriptProperties, 20);
$sort= $modx->getOption('sort', $scriptProperties, 'name');
$dir= $modx->getOption('dir', $scriptProperties, 'ASC');
$search= $modx->getOption('query', $scriptProperties,'');
$id= $modx->getOption('id', $scriptProperties, false);

$query= $modx->newQuery('modSnippet');
$query->innerJoin('modCategory','modCategory',array('`modCategory`.`id` = `modSnippet`.`category`'));
$query->where(array('`modCategory`.`category`'=>'mp'));

$count= $modx->getCount('modSnippet',$query);
//$query->sortby($sort, $dir);
$query->limit($limit, $start);

$snippets= $modx->getCollection('modSnippet', $query);

$list= array();
foreach($snippets as $snippet) {
	$list[]= $snippet->toArray();
}
return $this->outputArray($list, $count);

define('MODX_CORE_PATH', dirname(__DIR__).'/my_test_site/core/');