Undefined index in slideshow_fullscreen.php

Had two notices of undefined indexes from enfold/config-templatebuilder/avia-shortcodes/slideshow_fullscreen.php on lines:
923 and 926.
Fixed this by checking if the key existed first.

Line 923:

if(!empty($meta['index']) && $meta['index'] == 0) $params['close'] = false;

Line 926:

if(!empty($meta['index']) && $meta['index'] != 0) $params['class'] .= " slider-not-first";