After almost a full 24 hours, it seems the problem cleared up by itself (or I did something to fix it without realizing it). My code works and I was able to complete the Challenge. I guess you just have to wait for Khan Academy to realize your code isn't invalid.

I keep getting this runtime message every time I try to run my program. Is this a bug in Khan Academy or is something up with my code? I've ran the code multiple times without the input function and it works. This isn't a problem for this Challenge alone, either. I tested an input function on a different Challenge and it gave me the same error. This hasn't happened to me before and I can't find any fixes so I'm reaching out to the community for help.

I'd also like to mention (if this is a bug in Khan Academy) I've tried refreshing and it doesn't do anything.