PHP Notice Undefined variable

Hi,

Please, can you fix this notice :

PHP Notice: Undefined variable: class in /wp-content/plugins/my-favorites/assets/shortcode-list.php on line 90

Add this code at the line 77 :

if ($atts['class']) {
                $class = 'class="' . $atts['class'] . '"';
            } else {
                $class = null;
            }

Thank’s for your work

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