Something wrong with my heroku deployment - node.js

Question

`NPM_CONFIG_PRODUCTION=false npm install --prefix client && npm run build --prefix client`
remote: npm ERR! Exit status 254
remote: npm ERR!
remote: npm ERR! Failed at the walking-bucket#1.0.0 heroku-postbuild script.
This is the error I get when I try to deploy my express/React app to heroku, any ideas what is going wrong?
edit: package.json with build script:
{
"name": "walking-bucket",
"version": "1.0.0",
"description": "basketball shot journal log",
"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": "",
"license": "ISC",
"dependencies": {
"bcrypt": "^3.0.2",
"bcrypt-nodejs": "0.0.3",
"body-parser": "^1.18.3",
"concurrently": "^4.1.0",
"express": "^4.16.4",
"express-session": "^1.15.6",
"mongoose": "^5.3.14",
"passport": "^0.4.0",
"passport-local": "^1.0.0",
"passport-local-mongoose": "^5.0.1"
},
"devDependencies": {
"nodemon": "^1.18.7"
}
}

Answer 1

Got my solution with the build command
"build": "react-scripts build"
from the create-react-app package.json