So, a script I was developing was working fine yesterday, but today, it seems like my Array built-in object is broken. I tried restarting After Effects to reset the environment, but it's still broken. So far, I've identified that "map", "includes", and "split" are broken, though "shift" is fine. I don't have any custom startup scripts.
I've attached a simple .txt file that demonstrates this error for me, though I'm guessing it would work normally. Just rename it to .jsx and run it yourself.