Undefined Index Error

Website using the plugin: http://graybillcreative.com/underground
WordPress Version : 4.5.2
Instagram Slider Version : 1.3.2
Theme Name : Genesis
My Problem : I’m getting an undefined index error on the instagram widgets on the home page. This just showed up after I updated the plugin.

https://ww.wp.xz.cn/plugins/instagram-slider-widget/