How to show an error if there is no folder.

Code:
class MProducts extends Model{

 function MProducts(){

    parent::Model();

 }

...

...

/**

* This will add product

*/



function addProduct(){

    $data = $this->_uploadFile();

    $this->db->insert('omc_products', $data);



    ...

    ...    

 }

/**

* This will edit the product.

*/

function updateProduct(){

    $data = $this->_uploadFile();

     $this->db->where('id', $_POST['id']);

    $this->db->update('omc_products', $data);    

    $this->db->where('product_id', $_POST['id']);

    $this->db->delete('omc_products_colors');

    $this->db->where('product_id', $_POST['id']);

    $this->db->delete('omc_products_sizes'); 

     ...

     ...

 }



/**

  * This function will upload image and thumbnail and return $data['image']

  * and $data['thumbnail'] and other $_POST details data

  *

  */

 function _uploadFile(){

  $data = array( 

        'name' => db_clean($_POST['name']),

        'shortdesc' => db_clean($_POST['shortdesc']),

        'longdesc' => db_clean($_POST['longdesc'],5000),

        'status' => db_clean($_POST['status'],8),

        'class' => db_clean($_POST['class'],30),

        'grouping' => db_clean($_POST['grouping'],16),

        'category_id' => id_clean($_POST['category_id']),

        'featured' => db_clean($_POST['featured'],20),

        'price' => db_clean($_POST['price'],16),

        'other_feature' => db_clean($_POST['other_feature'],20)

    

    );

  $catname = array();

        $category_id = $data['category_id'];

        $catname = $this->MCats->getCategoryNamebyProduct($category_id);

        foreach ($catname as $key => $name){

        $foldername = strtolower($name);

        $foldername = str_replace(" ", "_", $foldername);

        }

       

    if ($_FILES){

        $config['upload_path'] = './images/'.$foldername.'/';

        $config['allowed_types'] = 'gif|jpg|png';

        $config['max_size'] = '200';

        $config['remove_spaces'] = true;

        $config['overwrite'] = true;

        $config['max_width']  = '0';

        $config['max_height']  = '0';

        

        $this->load->library('upload', $config);    

        if (strlen($_FILES['image']['name'])){

            if(!$this->upload->do_upload('image')){

                $this->upload->display_errors();

                exit();

            }

            $image = $this->upload->data();

            if ($image['file_name']){

                $data['image'] = "images/".$foldername."/".$image['file_name'];

            }

        }

        

        $config['upload_path'] = './images/'.$foldername.'/thumbnails/';

        $config['allowed_types'] = 'gif|jpg|png';

        $config['max_size'] = '200';

        $config['remove_spaces'] = true;

        $config['overwrite'] = true;

        $config['max_width']  = '0';

        $config['max_height']  = '0';

        //initialize otherwise thumb will take the first one

        $this->upload->initialize($config);

        

        if (strlen($_FILES['thumbnail']['name'])){

            if(!$this->upload->do_upload('thumbnail')){

                $this->upload->display_errors();

                exit();

            }

            $thumb = $this->upload->data();

            if ($thumb['file_name']){

                $data['thumbnail'] = "images/".$foldername."/thumbnails/".$thumb['file_name'];

            }

        }

    }

    return $data;

 }