{
  "name": "create-react-pwa",
  "version": "0.1.0",
  "private": true,
  "devDependencies": {
    "react-scripts": "0.7.0",
    "sw-precache": "^4.2.2"
  },
  "dependencies": {
    "react": "^15.4.0",
    "react-dom": "^15.4.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build && sw-precache --config='sw-precache-config.js'",
    "test": "react-scripts test --env=jsdom",
    "eject": "react-scripts eject"
  }
}

{
  "name": "create-react-pwa",
  "version": "0.1.0",
  "private": true,
  "devDependencies": {
    "react-scripts": "0.7.0",
    "sw-precache": "^4.2.2"
  },
  "dependencies": {
    "react": "^15.4.0",
    "react-dom": "^15.4.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build && sw-precache --config=sw-precache-config.js",
    "test": "react-scripts test --env=jsdom",
    "eject": "react-scripts eject"
  }
}

Remove '' from the build script
Remove '' from the build script