Undifined function

Hi there,

Im using your plugin for my site, it works perfectly in displaying the info i want it too but when i go to a page where there isnt any custom fields i get undifind function my code is below:

$iata = CFS()->get(false, 42, array('format' => 'raw'));

			if(!empty($iata)){ ?>

            <div class="afacts">

            <div class="afact">
            <div class="atitle">IATA</div>
            <div class="ainfo"><?php echo $iata; ?></div>
            </div>

            <div class="afact">
            <div class="atitle">ICAO</div>
            <div class="ainfo"><?php echo CFS()->get('icao'); ?></div>
            </div>

            <div class="afact">
            <div class="atitle">Operator</div>
            <div class="ainfo"><?php echo CFS()->get('operator'); ?></div>
            </div>

            <div class="afact">
            <div class="atitle">Airport Type</div>
            <div class="ainfo"><?php echo CFS()->get('airport_type'); ?></div>
            </div>

            <div class="afact">
            <div class="atitle">Coordinates</div>
            <div class="ainfo"><?php echo CFS()->get('coordinates'); ?></div>
            </div>

            </div>
            <?php }
}

https://www.ads-software.com/plugins/custom-field-suite/