I was addicted to rails at the beginning, so I took notes.
ExecJS::RuntimeError
Rails 5.2.4 ruby 2.5.1
Gemfile
gem 'mini_racer', platforms: :ruby
Uncomment the above and do a [bundle install] in the terminal and you're done.
ExecJS :: RuntimeError (2019 version) https://github.com/railsgirls-jp/coach.info/issues/27