title: Error parsing JSON: no implicit conversion of String into Integer
body: <p>My code: </p>
  
  <pre><code>    a = AppParam.find_by key: 'lowest_price'
  
      json.set! :response do
          json.array!(@products) do |product|
          json.extract! product, :id, :name, :description, :icon, :price, :tax, :is_active
          json.url product_url(product, format: :json)
      end
  
      json.extract! a, :value
  </code></pre>
  
  <p>Throws this error: </p>
  
  <pre><code>no implicit conversion of String into Integer in json.extratct! a, :value
  </code></pre>