Webpacker gem no longer provides yarn binstub

[asaletnik]

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I have just installed fresh versions of webpacker and react-rails gems today - running on Rails 4.2.8.

I followed the installation guide, and noticed that it throws some warning, but without failing:

rails generate react:install
       exist  app/javascript/components
   identical  app/javascript/components/.gitkeep
bin/rails: No such file or directory - /home/asaletnik/Apps/example-app/bin/yarn
      append  app/javascript/packs/application.js
   identical  app/javascript/packs/server_rendering.js

Ignored it at first, but quickly found out that it leads to webpack compile error, as without yarn the react_ujs module is missing:

ERROR in ./app/javascript/packs/application.js
Module not found: Error: Can't resolve 'react_ujs' in '/home/asaletnik/Apps/example-app/app/javascript/packs'
 @ ./app/javascript/packs/application.js 3:20-40
 @ multi (webpack)-dev-server/client?http://localhost:5001 ./app/javascript/packs/application.js

ERROR in ./app/javascript/packs/server_rendering.js
Module not found: Error: Can't resolve 'react_ujs' in '/home/asaletnik/Apps/example-app/app/javascript/packs'
 @ ./app/javascript/packs/server_rendering.js 4:20-40
 @ multi (webpack)-dev-server/client?http://localhost:5001 ./app/javascript/packs/server_rendering.js
webpack: Failed to compile.

This is related to a webpacker pull request merged just 4 days ago - rails/webpacker#367
For some reason they don't provide yarn binstub any more, instead they now call the executable directly.

The yarn binstub is still present in the Rails 5.1-stable:
https://github.com/rails/rails/blob/5-1-stable/railties/lib/rails/generators/rails/app/templates/bin/yarn

I have made a fork of react-rails and updated install_generator#setup_react_webpacker to use yarn executable directly as well - will add a Pull Request shortly.