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.**
chalk.white.bold(filename) + chalk.dim(` (${bundleType.toLowerCase()})`);
  const format = getFormat(bundleType);
  const packageName = Packaging.getPackageName(bundle.entry);
  let resolvedEntry = require.resolve(bundle.entry);
  if (bundleType === FB_DEV || bundleType === FB_PROD) {
    const resolvedFBEntry = resolvedEntry.replace('.js', '.fb.js');
    if (fs.existsSync(resolvedFBEntry)) {
      resolvedEntry = resolvedFBEntry;
    }
  }
  const shouldBundleDependencies =
    bundleType === UMD_DEV || bundleType === UMD_PROD;
  const peerGlobals = Modules.getPeerGlobals(
    bundle.externals,
    bundle.moduleType
  );
  let externals = Object.keys(peerGlobals);
  if (!shouldBundleDependencies) {
    const deps = Modules.getDependencies(bundleType, bundle.entry);
    externals = externals.concat(deps);
  }
  const importSideEffects = Modules.getImportSideEffects();
  const pureExternalModules = Object.keys(importSideEffects).filter(
    module => !importSideEffects[module]
  );
  console.log(`${chalk.bgYellow.black(' BUILDING ')} ${logKey}`);
  return rollup({
    input: resolvedEntry,
    pureExternalModules,
    external(id) {