It appears that the official chrome webstore extension by Rob W is outdated. It was last updated in 2019. 

const { AppOptions, OptionKind } = require("./" +
    DEFAULT_PREFERENCES_DIR +
    dir +
    "web/app_options.js");
  return AppOptions.getAll(OptionKind.PREFERENCE);
}
function getDialogPolyfillCSS() {
  return fs
    .readFileSync("node_modules/dialog-polyfill/dist/dialog-polyfill.css")
    .toString();
}
gulp.task("locale", function () {
  const VIEWER_LOCALE_OUTPUT = "web/locale/";
  console.log();
  console.log("### Building localization files");
  rimraf.sync(VIEWER_LOCALE_OUTPUT);
  mkdirp.sync(VIEWER_LOCALE_OUTPUT);
  const subfolders = fs.readdirSync(L10N_DIR);
  subfolders.sort();
  let viewerOutput = "";
  const locales = [];
  for (const locale of subfolders) {
    const dirPath = L10N_DIR + locale;
    if (!checkDir(dirPath)) {
      continue;
    }
    if (!/^[a-z][a-z]([a-z])?(-[A-Z][A-Z])?$/.test(locale)) {