Promise error handling with the Either pattern (disjunction)

promiseErrorHandling.js

import { Failure, Success } from 'data.validation';

// Report unhandled promise rejections (bugs)
window.onunhandledrejection = (event) => {
  // Raven.captureException(event.reason);
  console.error('Unhandled rejection:', event.reason);
};

function fetchRepo(name) {
  return fetch(`https://api.github.com/repos/${name}`).then((response) =>
    response.json().then((data) =>
      response.ok ? Success(data) : Failure(data)
    )
  );
}

function getStars(name) {
  fetchRepo(name).then((result) => {
    const message = result.fold(
      (error) => `Fetching '${name}' failed: ${error.message}`,
      (repo) => `${name}: ${repo.stargazers_count} stars`
    );
    console.log(message);
  });
}

getStars('babel/babel');
getStars('facebook/react');
getStars('fson/repo_does_not_exist');