The code is so old that their developers are already dead.

Exactly what I thought when I watched Doctor Strange and they talked about how spell is basically programming the world.

At this point Bob Howard shows up from another ficton and hoses the chalk circle down with dilute sulfuric acid.

I could never be a wizard. Mess up code, get some error messages. Mess up a spell, get turned into a pile of goo, slaughtered by a demon, or transported to a hell dimension.