auto in either schema is handled like none

[tingerrr]

It seems that c52ae78 introduced a regression where, given an either schema containing an auto schema, passing auto actually fails with an incorrect message saying it got none.

#import "@preview/valkyrie:0.2.0" as z

#{
  _ = z.parse(auto, z.either(
    z.content(),
    z.base-type(name: "auto", types: (type(auto),)),
  ))
}

I haven't actually tested this specific snippet, it's a minified version, I've done the bisection on the actual snippet.

[jamesrswift]

Tracked the issue down to base-type:

https://github.com/typst-community/valkyrie/blob/35-auto-in-either-schema-is-handled-like-none/src/base-type.typ#L82-L84

I think the most sensible solution would be to provide default: auto when defining the auto schema? that does then mean that passing none as the value makes it mutate into auto.

What are your thoughts? I don't think there's a clean solution