undefined index error in catalog.tpl in opencart

Question

I have the following error everything I click on a category:

Notice: Undefined index: listing_products_columns in /home/tkvtoys/public_html/catalog/view/theme/TKV/template/product/category.tpl on line 21

<?php 
require_once( DIR_TEMPLATE.$this->config->get('config_template')."/development/libs/framework.php" );
$themeName =  $this->config->get('config_template');
$helper = ThemeControlHelper::getInstance( $this->registry, $themeName );

require( DIR_TEMPLATE.$this->config->get('config_template')."/template/common/config.tpl" ); 
$themeConfig = (array)$this->config->get('themecontrol');

$categoryConfig = array( 
 'listing_products_columns'          => 0,
 'listing_products_columns_small'        => 2,
 'listing_products_columns_minismall'     => 1,
 'cateogry_display_mode'          => 'grid',
 'category_pzoom'               => 1, 
 'quickview'                                 => 0,
 'show_swap_image'                        => 0,
 ); 

$categoryConfig   = array_merge($categoryConfig, $themeConfig );
$DISPLAY_MODE    = $categoryConfig['cateogry_display_mode'];
$MAX_ITEM_ROW    = $themeConfig['listing_products_columns']?$themeConfig['listing_products_columns']:3; 
$MAX_ITEM_ROW_SMALL = $categoryConfig['listing_products_columns_small']?$categoryConfig['listing_products_columns_small']:2;
$MAX_ITEM_ROW_MINI  = $categoryConfig['listing_products_columns_minismall']?$categoryConfig['listing_products_columns_minismall']:1; 
$categoryPzoom      = $categoryConfig['category_pzoom']; 
$quickview          = $categoryConfig['quickview'];
$swapimg            = $categoryConfig['show_swap_image'];

?>

anyone knows how to fix this ?