Return something when tutor images build contains a typo

Currently tutor images build opneedx returns nothing. It may take a newcomer sometime to figure out the typo. Maybe some improvements can be done, like return cannot find image "opneedx" to build

Yes, I agree. And the error message should be similar for tutor images pull and push commands. I propose a fix here: feat: fail `images build/pull/push` commands on incorrect image arg by regisb · Pull Request #535 · overhangio/tutor · GitHub