code: func GetManifest(publicPath string) (map[string]string, error) {
  	manifestPath := filepath.Join(publicPath, "assets", "manifest.json")
  	contents, err := ioutil.ReadFile(manifestPath)
  	if err != nil {
  		return nil, err
  	}
  	if len(contents) == 0 {
  		return nil, errors.New("manifest.json is empty")
  	}
  
  	manifest := map[string]string{}
  	err = json.Unmarshal(contents, &manifest)
  	if err != nil {
  		return nil, errors.Wrap(err, "cannot unmarshal manifest.json")
  	}
  	if len(manifest) == 0 {
  		return nil, errors.New("manifest.json has no file mappings")
  	}
  
  	return manifest, nil
  }
docs: // GetManifest reads the manifest.json file in the public assets folder
  // and returns a map of its mappings. Returns error if manifest.json not found.