Found a solution. In google-auth.js change
const config = {
  auth: {
    keyFilePath: path.resolve(__dirname,     '../assets/google-client-secret.json'), // secret.json
    savedTokensPath: path.resolve(__dirname, '../assets/google-access-tokens.json'), // resources/tokens.js
  },
}
to
const config = {
    keyFilePath: path.resolve(__dirname,     '../assets/google-client-secret.json'), // secret.json
    savedTokensPath: path.resolve(__dirname, '../assets/google-access-tokens.json'), // resources/tokens.js
}