I have recently completed a MEVN stack app but have trouble deploying it to Heroku. I contacted their support but they have trouble helping me too, and claim that it may be code or routing related. They also don’t offer code support. I’m also unsure if whether it is a core-related or Heroku configuration-related issue. What actually happens is that the app is deployed successfully but it doesn’t display.

deployment url

GitHub project URL

As you can see, the app is not displayed correctly even though the deployment succeeds. You can examine the entire codebase on the GitHub link provided above, and I would appreciate any suggestions of what may be wrong and how I should fix it.