report multiple errors at once

[Gankra]

Right now we do the normal thing of just returning Results and failing as soon as we hit an error.

miette lets you have errors that contain multiple other errors and I've done that before. Or we could do the more rustc thing of shooting off errors into some ~logger system and just returning a dummy Error type with no payload.

However multiple errors often requires some amount of recovery and faking values. rustc apparently has a habit of adding an extra Err variant to many of its enums to represent things like "a type that probably exists but is garbage" so that you can keep moving along and just be quiet when something requires garbage.