Have you been able to successfully run `yarn install`? The error message `node_modules doesn't exist or is not a directory` makes me think that the JS Libraries and dependencies haven't been installed yet.
Sorry, I mean on heroku.
Try and whatever else buildpacks needed for your application (if any)
```
heroku buildpacks:clear
heroku buildpacks:set heroku/nodejs
heroku buildpacks:add heroku/ruby
```
It was a popular episode suggestion where due to compliance regulations (COPPA, CCPA, GDPR) they wanted to move from having an internal authorization mechanism to more of a hosted solution.
Personally, I think in most cases Devise + Omniauth is suitable enough and I probably wouldn't implement Auth0. However, not having to worry about the authentication security portion is nice. Then again, if Auth0 is ever down, then from your end users' perspective, for all intents and purposes, you're site is also "down".
