Unexpected validation pass about nested fields

[vmarcosp]

@mununk reported on ReForm (rescriptbr/reform#244):

I encounter a weird unexpected validation pass about the nested field array. Here is my example:

module ProfileFormFields = %lenses(
  type t = {
    nickname: string,
    age: int,
  }
)

module FormFields = %lenses(
  type state = {
    name: string,
    email: string,
    profiles: array<ProfileFormFields.t>,
  }
)

module Form = ReForm.Make(FormFields)
...
        schema([
          custom(({profiles}) => {
            let errors: array<ReSchema.childFieldError> = // <-- 1
              profiles
              ->Array.mapWithIndex((index, profile) =>
                if profile.nickname == "" || profile.age <= 0 {
                  let error: ReSchema.childFieldError = {
                    error: "Invalid profile",
                    index,
                    name: "???",
                  }
                  Some(error)
                } else {
                  None
                }
              )
              ->Array.keepMap(x => x)

            switch errors {
            | [] => Valid
            | _ => NestedErrors(errors) // <- 2. return NestedErrors!
            }
          }, Profiles)
        ])
...

Field(Profiles)->form.getNestedFieldError(index)->Js.log // errors are all None??

The length of errors in comment:1 is not 0, so it means that this predicate function returns NestedErrors(errors). But none of the indexes in the nested field has an error. So, the submission proceeded even though the nested fields are not satisfied in the custom schema.

I guess that validate function (https://github.com/rescriptbr/reschema/blob/master/src/ReSchema.res#L287:L292) in ReSchema should check the NestedErrors there. Or anything I missed for the nested fields validation?

[vmarcosp]

cc @fakenickels @mununki