Deploying static React App to Heroku, but getting application error. Getting a H13 and H10 error when I run Heroku logs --tail

I'm deploying my static React app (purely front end, no API, no node.js, no express- just front end). It works fine locally, and I was able to successfully build it to Heroku. When I run heroku open through git bash on my windows os, the browser window opens with my heroku site as it should, but it says application error on the site. I run heroku logs --tail and sometimes I get an H13 error, but always get a H10 error. I've pasted the errors below. I've included the versions of npm and node in engines in my package json, and I've looked at the Heroku error codes(https://devcenter.heroku.com/articles/error-codes#h13-connection-closed-without-response) and I'm not getting any solutions. I've also searched all over stackoverflow and haven't found any solutions that help me. The error codes are below, and I've replaced what I think to be sensitive and irrelevant information with asterisks. I'm not too familiar with stackoverflow, and any help would be appreciated!

heroku[router]: at=error code=H13 desc="Connection closed without response" method=GET path="/" host=****.herokuapp.com request_id=**** fwd="****" dyno=web.1 connect=1ms service=19004ms status=503 bytes=0 protocol=https 2020-02-29T19:42:51.522926+00:00 heroku[web.1]: State changed from up to crashed 2020-02-29T19:42:51.503699+00:00 heroku[web.1]: Process exited with status 1 2020-02-29T19:42:52.101343+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=****.herokuapp.com request_id=**** fwd="****" dyno= connect= service= status=503 bytes= protocol=https

package json

{
  "name": "nhreact",
  "version": "0.1.0",
  "private": true,
  "engines": {
    "npm": "6.12.0",
    "node": "12.13.0"
  },
  "dependencies": {
    "@testing-library/jest-dom": "^4.2.4",
    "@testing-library/react": "^9.3.3",
    "@testing-library/user-event": "^7.1.2",
    "jquery": "^3.4.1",
    "node-sass": "^4.13.1",
    "radium": "^0.26.0",
    "react": "^16.12.0",
    "react-dom": "^16.12.0",
    "react-router-dom": "^5.1.2",
    "react-scripts": "3.3.0",
    "three": "^0.113.2",
    "vanta": "^0.5.10"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}