code: function generateIndexEntry(isDev) {
      const indexEntry = [];
  
      if (isDev) {
          indexEntry.push(`webpack-dev-server/client?${PROTOCOL}://${HOST}:${PORT}/`);
          indexEntry.push('webpack/hot/only-dev-server');
      }
  
      indexEntry.push(paths.appIndexJs);
  
      return indexEntry;
  }
docs: Helpers