So this is a pretty minor and reseting the page fixes it. I sometimes run a test alert to check if a button is linked to a function, doing this in the react course however seems to open a cascading series of windows in the display area of the page. Its pretty easy to avoid (by not running alert) and easy to fix.
Minor Bug in the React Course
Thank you for helping to make FCC better. Would you mind creating a detailed GitHub Issue which describes this bug?