When I try on an existent app:
rails vue:setup

and is giving this error

`
You are using Vue on Rails 1.0.0.beta5 and it does not support webpacker 4.

Please use the latest Vue on Rails (1.x) in your Gemfile:
  gem 'webpacker', '~> 4.x'
  gem 'vueonrails', '~> 1.x'

or switch back to webpacker 3:
  gem 'webpacker', '~> 3.x'
  gem 'vueonrails', '~> 0.x'

ruby '2.5.3'
gem 'rails', '> 5.2.3'
gem 'webpacker', '> 4.x'
gem 'vueonrails', '~> 1.x'
`