refer to: https://stackoverflow.com/questions/54113179/rails-webpackermanifestmissingentryerror-in-homeindex
bundle exec rails webpacker:install
同时参考: https://stackoverflow.com/questions/65858869/webpacker-cant-find-application-css-in-app-public-packs-manifest-json/71509602#71509602
bundle exec rails s -p 3000 # port 3000
bundle exec bin/webpack-dev-server # port 3030