Can't visualize my scatterplot

hi everyone,

I built my first scatterplot on my own from the lessons here on FCC, but I couldn’t make it work even though I was following the logic and I thought I understood it. So I decided to build it again following a tutorial. I did so, but… the chart doesn’t even show on my SVG. I can the SVG itself and the rect but that’s about it. I checked that I have the same d3 version as the person in the tutorial, etc. but I can’t wrap my head around why it’s not showing.

Can someone help me with this? here’s my pen:


I didn’t look too carefully into the code, and I am not sure about what’s the problem, but there is this error: “TypeError: d3.event is null”, when I look into the browser console with ctrl+shift+i.
Where and why did you use d3.event?