stop invalid json after calling to_json on active model errors

active_model_errors_patch.rb

module ActiveModel
  class Errors
    def as_json(options=nil)
      self
      to_hash
    end

    def to_hash
      hash = ActiveSupport::OrderedHash.new
      each { |k, v| (hash[k] ||= []) << v }
      hash
    end
  end
end