Missing assets/front/images/ribbons/none.png file?

I am getting 404 error messages on this file: assets/front/images/ribbons/none.png. The none.png file looks like it’s referenced in the assets/front/css/style.css. I’ve looked through a few earlier versions of the plugin but it doesn’t appear to be in those either. Is this a required file?

https://www.ads-software.com/plugins/woocommerce-products-slider/