Fatal Error : Line 60 of wc_yotpo

[09-Nov-2014 12:02:11 UTC] PHP Fatal error: Call to undefined function is_product() in /home/xxx/public_html/wp-content/plugins/yotpo-social-reviews-for-woocommerce/wc_yotpo.php on line 60

As above. Keep finding debug.log showing this error 🙁

https://wordpress.org/plugins/yotpo-social-reviews-for-woocommerce/