Use message properties returns Api.Type* instead Api.* Is any automatic type conversion or methods to take concrete type

[aam1go]

Need some help with using object properties in gramjs.

Have message:
const message = event.message;
For example, I want to get photo from this message contains photo. Using:

const photo = message.photo; // Expect type Api.InputPhoto, but returns Api.TypeInputPhoto.
//I can use "as Api.InputPhoto"
const photo = messages.photo as Api.InputPhoto;

but if I need to go deeper into properties. I should cast Api.Type* -> Api.* everywhere.
Is any decision without type casting?