The goal is that until the user has mapped exactly one X and two or more Y fields, they will continue to see an error like this:
What actually happens is that you can't map any fields at all.
We could set up multiple conditions as "stepping stones" to get to the condition shown above, but that would completely defeat the purpose. The goal here is to display the included error message until the user has mapped all the necessary fields.
Is this possible, or will we need to implement our own input validation and error display?