Answers for "line 22: 'app' is not defined no-undef"

process' is not defined.eslint no-undef

in your eslint file .eslintrc.json or .eslintrc.js file
make sure you include either node or browser "true"

check example

module.exports = {
  env: {
    node: true,
    browser: true,
    es6: true,
  },
}

'App' is not defined react/jsx-no-undef

import Map from './Map';