Incompatible with ActiveModel 6.1

[rewritten]

The ActiveModel::Errors class has changed, keeping most of the high level API compatible, but some of the underlying implementation are not working anymore.

The class ActiveData::Model::Validations::NestedValidator is not compatible with the new implementation, it should be something on the lines of:

def self.validate_nested(record, name, value)
  if value.is_a?(Enumerable)
    value.each.with_index do |object, i|
      if yield(object)
        object.errors.each do |error|
          record.errors.import(error, attribute: "#{name}.#{i}.#{error.attribute}")
        end
      end
    end
  elsif value && yield(value)
    value.errors.each do |error|
      record.errors.import(error, attribute: "#{name}.#{error.attribute}")
    end
  end
end

but of course this only works with the new errors interface… so maybe a version check? I haven't been able to find a version-independent way to achieve it.