NoMethodError: undefined method `serializable_hash' for #<Hash:0x00007fc3ef69c278> when error entity has root

Hello.
I try to add error root for errors.

class API::Error < Grape::Entity
  root 'errors', 'error'
  expose :code
  expose :message
end

error!({ message: "Some error", code: 123, with: API::Error }, 400)

When error entity has root element, I have error:

NoMethodError: undefined method `serializable_hash' for #<Hash:0x00007fc3ef69c278>
	/Users/nikolay/.rbenv/versions/2.4.4/lib/ruby/gems/2.4.0/gems/grape-1.1.0/lib/grape/error_formatter/base.rb:29:in `present'

Because Grape::Entity#represent method can return entity or hash, but
Grape::ErrorFormatter::Base#present is not ready for this result, and called to serializable_hash whatever the result.

Start in lib/grape/error_formatter/base.rb:29 and compare its present handling with Grape::Entity#represent in grape-entity/lib/grape_entity/entity.rb. Reproduce the reported error! call using an entity with a root, then trace whether the result is an entity or Hash. Done means the rooted error formats without NoMethodError and preserves the expected error response.