/* Check favicon middleware
function registerFavicon(app, config) {
    if (typeof config.static !== 'string' || !config.static) return;
    let stat;
    // check .ico
    try {
      stat = fs.lstatSync(config.static + '/favicon.ico');
      if (stat.isFile()) return;
    } catch (e) {
      if (e.code !== 'ENOENT') return;
    }
    let faviconFn = initFavicon(thorin, config);
    if (!faviconFn) return;
    app.use(faviconFn);
  }