Currently when the build fails (e.g. due to a missing named export), the message is pretty ugly:

<img width="1033" alt="screen shot 2017-11-04 at 13 12 31" src="https://user-images.githubusercontent.com/810438/32405680-d618d2e6-c161-11e7-9b91-e0241c7c3eed.png">

It would be nice to display the relevant line inline with syntax highlighting, sort of like Babel does it. Maybe Babel's `babel-code-frame` could be helpful (not sure).

To reproduce, fail the build by removing some `export` somewhere and run `yarn build`. (Tip: `yarn build core --type=NODE_DEV` is the fastest way to build just `packages/react/*` and that might be enough to reproduce and iterate on the error message.)

The relevant logic for displaying build errors is probably somewhere in `scripts/rollup/build.js`.

**If you'd like to work on this please comment here, so we don't have many people working on the same thing.**
fs.mkdirSync('build');
  
  fs.mkdirSync(join('build', 'packages'));
  
  fs.mkdirSync(join('build', 'dist'));
  const tasks = [
    Packaging.createFacebookWWWBuild,
    Packaging.createReactNativeBuild,
    Packaging.createReactNativeRTBuild,
    Packaging.createReactNativeCSBuild,
  ];
  for (const bundle of Bundles.bundles) {
    tasks.push(
      () => createBundle(bundle, UMD_DEV),
      () => createBundle(bundle, UMD_PROD),
      () => createBundle(bundle, NODE_DEV),
      () => createBundle(bundle, NODE_PROD),
      () => createBundle(bundle, FB_DEV),
      () => createBundle(bundle, FB_PROD),
      () => createBundle(bundle, RN_DEV),
      () => createBundle(bundle, RN_PROD)
    );
  }
  if (syncFbsource) {
    tasks.push(() =>
      syncReactNative(join('build', 'react-native'), syncFbsource)
    );
    tasks.push(() =>
      syncReactNativeRT(join('build', 'react-rt'), syncFbsource)