The terminal will always show the same Color(0, 0, 0) as the image of the actor does not change. You can bump up the speed of the scenario to help eliminate wait time as the background fills in.
Thanks Dan,
It turns out that this wasn't the actual problem. I was getting a javascript error that made it seem like setColorAt was getting a null object. It turned out that I was hitting an object limit. Once I simplified some of my classes to maintain a spritesheet rather than a number of arrays of GreenfootImage, it eliminated the problem.
This is the scenario I'm working on, if you're interested: https://www.greenfoot.org/scenarios/25314
2020/2/22
2020/2/24
2020/11/1