Docs: Prevent virtual types reaching docs generator

[bcardiff]

Fixes #6201

I was unable to reduce the code for a short repro. But somehow the Lucky::Routeable managed to produce some virtual types that were not handled in the docs generator.

Virtual types does not make sense in the doc generator since from the user perspective they are always substitutable by a subclass. That is what virtual types represent inside the compiler, while a type is an exact reference. This serves mainly during the codegen.

@paulcsmith, would you mind checking the the output is the expected one? The method that complained was Lucky::Route#action that was returning a virtual type of Lucky::Action.class

[paulcsmith]

Thanks @bcardiff! Just to be clear, do you want me to pull this branch done and try to use it to generate docs for Lucky?

[bcardiff]

I did and the docs were generated. So far the output seems right, but you might want to double check it. So, yes please if you want :-)

[paulcsmith]

Awesome! Thanks so much for the fix. I'm excited to give it a try