npm start command not found in create-react-app -- how to add to package.json?

Question

sh: react-scripts: command not found
 

npm ERR! Missing script: "start"
npm ERR! 
npm ERR! Did you mean one of these?
npm ERR!     npm star # Mark your favorite packages
npm ERR!     npm stars # View packages marked as favorites
npm ERR! 
npm ERR! To see a list of scripts, run:
npm ERR!   npm run