if single_not_embedded_field:
        field_info = first_field.field_info
        assert isinstance(field_info, params.Param), (
            "Params must be subclasses of Param"
        )
        loc: tuple[str, ...] = (field_info.in_.value,)
        v_, errors_ = _validate_value_with_model_field(
            field=first_field, value=params_to_process, values=values, loc=loc