We should upgrade webpacker gem and webpack npm package to v5 (and eventually to v6)
In order to be able to upgrade we first need to upgrade to Rails 5.2 and Node 12.
Once Rails 5.2 and Node 12 are ready, we should:
- Update webpacker / webpack to latest 4.X and every single plugin, loader, libs, etc...
- Upgrade to webpacker 5 , then run webpacker isntalll, then probably upgrade webpack with yarn
- Update every loader, lib, etc... again
- build packs, fix errors and
- click test
- After v5 is running, upgrade to v6, if possible.