Remove the package-lock.json

for some reason this won't currently deploy to Heroku, it gives an error while building dependencies:
Building dependencies
Installing node modules (package.json + package-lock)
npm ERR! Buffer.alloc is not a function

it looks like an issue with something specified in package-lock.json generated when doing npm install. Doing an npm update cors/express -s (and then correcting the package-lock.json) worked for me?