I'm working on a framework-level-esque method that deserializes some JSON from a framework-level config store. I want the calling code to be able to specify a validator that would essentially confirm that a strict-shape is being returned.

I've tried to simplify it for the playground into this example: https://phpstan.org/r/c2d1ee2a-0fde-4e30-9bd9-032a6fd3cea1

However, I'm running into one major issue: It seems like phpstan can't use conditional returns referencing a callable's parameters.

Am I completely off-base here? Should I be doing it some other way? Is it simply not possible with phpstan?

I'd really appreciate any suggestions or advice!