・ Ruby: 2.5.7 Rails: 5.2.4 ・ Vagrant: 2.2.7 -VirtualBox: 6.1 ・ OS: macOS Catalina
The following has been implemented.
//Change before //= require_tree //Change before // require_tree
If you want to reflect it in the development environment,
production.rb if you want to reflect it in the production environment.