Okay so I was able to fix the problem in production (without dev client), and discovered that the issue is related to this other issue I was having that is discussed here:
I had done some strange stuff with registerRootComponent in order to fix the “illegal operation” error in development, but whatever I did was causing the “Element type is invalid” issue in production.
So, for the moment, my app errors out in development, but works in production. And the only fix I’ve found ends up breaking the app in production. What a world!