Ruby - Getting Started with Rails - El objeto no acepta esta propiedad o método

Saludos.

Estoy intentando iniciar con Ruby On Rails y estoy siguiendo el tutorial "Getting Started with Rails". Cuando me pide que haga un cambio en el archivo routers.rb me da error. Adjunto imagen del error.

Muchas gracias de antemano.

Rails.application.routes.draw do
get 'welcome/index'

# For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
end
This is your application's routing file which holds entries in a special DSL (domain-specific language)that tells Rails how to connect incoming requests to controllers and actions. Edit this file by adding the line of code root 'welcome#index'. It should look something like the following:

Rails.application.routes.draw do
get 'welcome/index'

root 'welcome#index'
end

Me respondo a mi mismo. Faltaba instalar Node.js