Always use memory_store in development

Not only when tmp/caching-dev.txt exists

config/environments/development.rb

@@ -17,20 +17,18 @@
   # Enable server timing
   config.server_timing = true
 
+  config.cache_store = :memory_store
   # Enable/disable caching. By default caching is disabled.
   # Run rails dev:cache to toggle caching.
   if Rails.root.join("tmp/caching-dev.txt").exist?
     config.action_controller.perform_caching = true
     config.action_controller.enable_fragment_cache_logging = true
 
-    config.cache_store = :memory_store
     config.public_file_server.headers = {
       "Cache-Control" => "public, max-age=#{2.days.to_i}"
     }
   else
     config.action_controller.perform_caching = false
-
-    config.cache_store = :null_store
   end
 
   # Print deprecation notices to the Rails logger.