Only mount graphiql in development environment

Gemfile

@@ -66,7 +66,6 @@ gem 'turnout', '~> 2.4.0'
 gem 'redcarpet'
 
 gem 'graphql'
-gem 'graphiql-rails'
 
 group :development, :test do
   # Call 'byebug' anywhere in the code to stop execution and get a debugger console
@@ -104,6 +103,7 @@ end
 group :development do
   # Access an IRB console on exception pages or by using <%= console %> in views
   gem 'web-console', '3.3.0'
+  gem 'graphiql-rails'
 end
 
 eval_gemfile './Gemfile_custom'

config/routes.rb

@@ -265,12 +265,12 @@ Rails.application.routes.draw do
   end
 
   # GraphQL
-  mount GraphiQL::Rails::Engine, at: '/graphiql', graphql_path: '/graphql'
   get '/graphql', to: 'graphql#query'
   post '/graphql', to: 'graphql#query'
 
   if Rails.env.development?
     mount LetterOpenerWeb::Engine, at: "/letter_opener"
+    mount GraphiQL::Rails::Engine, at: '/graphiql', graphql_path: '/graphql'
   end
 
   mount Tolk::Engine => '/translate', :as => 'tolk'