Unable to deploy app to Heroku. Where is the mistake?

Question

Node.js

I made a react app using linter. In the early stages, everything worked as it should. The application started.
I recently deployed the app to Heroku again and got this error: .
What could be the problem? It works on LAN, but not on Heroku.
I would be grateful if someone could help.
UPD: at first the application renders normally, and then an error appears, which is on the screenshot above.

Answer 1

Why - heroku + lint, what is the "brother" feature