["Invalid property" "y" "set to" -10 "Missing plugin? gsap.registerPlugin()"]

@PointC  Thank you for the prompt response, I will have to keep an eye on my es6 usage. @ZachSaucier  Thanks for the additional tips and I agree, Vanilla JS is usually the way to go but I was mostly focusing on GSAP in this course, not so much Javascript. 

["Invalid property" "y" "set to" -10 "Missing plugin? gsap.registerPlugin()"]

Hello. My name is Michael, I am currently located in the Florida panhandle area.  I am new to GSAP and I am getting errors I don't understand. I have been a web developer for around 7 years. I am following a GSAP course from udemy and ran into some issues. Please look at my codepen and let me know any suggestions you may have. Thank you. 

See the Pen zYKNrWx?editors=1111 by Kustomdesigner (@Kustomdesigner) on CodePen