getAssetFiles(assets) {
    const files = _uniq(
      Object.keys(assets)
        .filter((assetType) => assetType !== "chunks" && assets[assetType])
        .reduce((files, assetType) => files.concat(assets[assetType]), []),
    );
    files.sort();
    return files;
  }
Helper to return a sorted unique array of all asset files out of the asset object
@private