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.**
);
    tasks.push(() =>
      syncReactNativeCS(join('build', 'react-cs'), syncFbsource)
    );
  } else if (syncWww) {
    tasks.push(() => syncReactDom(join('build', 'facebook-www'), syncWww));
  }
  
  
  
  return runWaterfall(tasks)
    .then(() => {
      
      console.log(Stats.printResults());
      
      Stats.saveResults();
      if (shouldExtractErrors) {
        console.warn(
          '\nWarning: this build was created with --extract-errors enabled.\n' +
            'this will result in extremely slow builds and should only be\n' +
            'used when the error map needs to be rebuilt.\n'
        );
      }
    })
    .catch(err => {
      console.error(err);
      process.exit(1);
    });
});
function runWaterfall(promiseFactories) {