Modern Front-End Development for Rails: Can't get past the entire first chapter

Trying to build an app from scratch based off of the first chapter is extremely frustrating when trying to use the later/latest versions of related libraries.

I’m using Rails 6.1.4.1 and Webpacker v6.0.0.rc.5:

rails new side_project -d postgresql

gem 'webpacker', github: 'rails/webpacker' (6.0.0.rc.5 at time of installation)

After running rails webpack:install, by default the rails app uses app/javascript/packs instead of app/packs/entrypoints. I renamed the folders to follow the same pattern as in the book.

Second, application.scss does not exist, only application.css in app/assets/stylesheets/application.css, so if we need to rename and copy it over to packs/entrypoints/ it’s unclear.

fork-ts-checker-webpack-plugin is required in the config mentioned on p 57 but it’s not mentioned anywhere that this has to be added with yarn first. yarn add fork-ts-checker-webpack-plugin.

Last, I had to update webpacker.yml to update the source_path and source_entry_path to match the new folder structure:

default: &default
  source_path: app/packs
  source_entry_path: entrypoints
  public_root_path: public
  public_output_path: packs
  cache_path: tmp/webpacker
  webpack_compile_output: true

Even after all this config change, I cannot get the app to compile:
Webpacker can't find application.js

Here is a sample repo where I’ve tried to get this to work, any help would be much appreciated.

EDIT:

Was finally able to get my app to run. It required doing a few different things, some from the webpacker 6 upgrade guide: webpacker/v6_upgrade.md at master · rails/webpacker · GitHub

1. delete .browserlistrc
2. delete babel.config.js
3. yarn add postcss-flexbugs-fixes postcss-import postcss-preset-env (this is especially annoying because they are required inside postcss.config.js by default)
4. Add a dummy TS file to entrypoints/ or tsconfig.json will complain. I added a empty dummy.ts file.

The lack of documentation for all the config that is required with rails new along with a fresh install of webpacker 6 is unfortunate, hopefully things can be updated soon.