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.**
const containsThisModule = pkg => id === pkg || id.startsWith(pkg + '/');
      const isProvidedByDependency = externals.some(containsThisModule);
      if (!shouldBundleDependencies && isProvidedByDependency) {
        return true;
      }
      return !!peerGlobals[id];
    },
    onwarn: handleRollupWarnings,
    plugins: getPlugins(
      bundle.entry,
      externals,
      bundle.babel,
      filename,
      bundleType,
      bundle.global,
      bundle.moduleType,
      bundle.modulesToStub,
      bundle.featureFlags
    ),
    
    legacy: bundleType === FB_DEV || bundleType === FB_PROD,