Deferred is passed to field resolvers as-is

[MidnightDesign]

Basically, I'm getting this error:

CityId::__invoke(): Argument #1 ($city) must be of type MyCity, GraphQL\\Deferred given, called in /(...)/MyCustomResolver.php on line 36

...where CityId is my field-specific resolver and MyCustomResolver is a resolver that builds the CityId class name from the type and field name. I'm using React and the ReactPromiseAdapter.

I don't understand why the Deferred is not being resolved. I think I've tracked the problem down to ReferenceExecutor::getPromise(), which is called by completeValueCatchingError(). I would expect it to turn the Deferred into a Promise, but it doesn't.

Do I have to return React Promises instead of Deferred from my resolvers if I'm using React? Nah, that would defeat the purpose of Deferred entirely, right?

I'm at a loss, please help. : )

[MidnightDesign]

I've been stuck on this for hours, but of course I stumble upon the solution just moments after I've posted this question.

It says it in the docs:

Then your resolve functions should return promises of your platform instead of GraphQL\Deferreds.