If we can cover 99% of the use cases without setting the `schemaExtension`, I'd be tempted to remove it as an option to avoid misuse and bring it back when we have a real use case for it.

I realize that deployers will have to maintain a patch to config.js for things to work (as things stand), which is exactly why I'd like to keep things like this, that might depend on a new feature being added, out of config.js.