Nodejs app with Heroku failing on "react-scripts: Permission denied" - node.js

Question

I am trying to push my app to Heroku, but I am getting an error when it gets to the heroku postbuild script:
remote: > NPM_CONFIG_PRODUCTION=false npm install --prefix client && npm run build --prefix client
remote:
remote: audited 905058 packages in 15.807s
remote: found 0 vulnerabilities
remote:
remote:
remote: > client#0.1.0 build /tmp/build_b7466d5902dcde0a3dc95258046c08c6/client
remote: > react-scripts build
remote:
remote: sh: 1: react-scripts: Permission denied
remote: npm ERR! code ELIFECYCLE
remote: npm ERR! errno 126
remote: npm ERR! client#0.1.0 build:react-scripts build
remote: npm ERR! Exit status 126
remote: npm ERR!
remote: npm ERR! Failed at the client#0.1.0 build script.
remote: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
remote:
remote: npm ERR! A complete log of this run can be found in:
remote: npm ERR! /tmp/npmcache.CXg0t/_logs/2019-10-17T19_19_39_823Z-debug.log
remote: npm ERR! code ELIFECYCLE
remote: npm ERR! errno 126
remote: npm ERR! safety-influence#1.0.0 heroku-postbuild:NPM_CONFIG_PRODUCTION=false npm install --prefix client && npm run build --prefix client
remote: npm ERR! Exit status 126
remote: npm ERR!
remote: npm ERR! Failed at the safety-influence#1.0.0 heroku-postbuild script.
remote: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
remote:
remote: npm ERR! A complete log of this run can be found in:
remote: npm ERR! /tmp/npmcache.CXg0t/_logs/2019-10-17T19_19_39_835Z-debug.log
Here is my package.json folder on the server side:
{
"name": "safety-influence",
"version": "1.0.0",
"description": "",
"engines": {
"node": "12.3.1"
},
"main": "server.js",
"scripts": {
"client-install": "npm install --prefix client",
"start": "node server.js",
"server": "nodemon server.js",
"client": "npm start --prefix client",
"dev": "concurrently \"npm run server\" \"npm run client\"",
"heroku-postbuild": "NPM_CONFIG_PRODUCTION=false npm install --prefix client && npm run build --prefix client"
},
"author": "David Jaenike",
"license": "ISC",
"dependencies": {
"bcryptjs": "^2.4.3",
"body-parser": "^1.19.0",
"concurrently": "^4.1.2",
"express": "^4.17.1",
"gridfs-stream": "^1.1.1",
"is-empty": "^1.2.0",
"jsonwebtoken": "^8.5.1",
"mongoose": "^5.7.3",
"multer": "^1.4.2",
"multer-gridfs-storage": "^3.3.0",
"nodemon": "^1.19.3",
"passport": "^0.4.0",
"passport-jwt": "^4.0.0",
"validator": "^11.1.0"
},
"devDependencies": {
"nodemon": "^1.19.1"
}
}
and on the client side:
{
"name": "client",
"version": "0.1.0",
"private": true,
"dependencies": {
"axios": "^0.19.0",
"classnames": "^2.2.6",
"file-saver": "^2.0.2",
"jwt-decode": "^2.2.0",
"moment": "^2.24.0",
"react": "^16.10.1",
"react-app-polyfill": "^1.0.4",
"react-dom": "^16.10.1",
"react-redux": "^7.1.1",
"react-router-dom": "^5.1.2",
"react-scripts": "^3.2.0",
"redux": "^4.0.4",
"redux-thunk": "^2.3.0",
"sweetalert2": "^8.18.0",
"sweetalert2-react-content": "^1.1.0"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"proxy": "http://localhost:80",
"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"
]
},
"devDependencies": {
"react-social-icons": "^4.1.0"
}
}
I have tried running npm install on both the server and client side again, and have also deleted, the reinitialized the git repository. No luck. ANyone have any advice on how to get this build working?