The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
console.log();
  console.log("### Creating web site");
  rimraf.sync(GH_PAGES_DIR);
  
  return merge([
    vfs
      .src(GENERIC_DIR + "**/*", { base: GENERIC_DIR, stripBOM: false })
      .pipe(gulp.dest(GH_PAGES_DIR)),
    vfs
      .src(GENERIC_LEGACY_DIR + "**/*", {
        base: GENERIC_LEGACY_DIR,
        stripBOM: false,
      })
      .pipe(gulp.dest(GH_PAGES_DIR + "legacy/")),
    gulp
      .src(JSDOC_BUILD_DIR + "**/*", { base: JSDOC_BUILD_DIR })
      .pipe(gulp.dest(GH_PAGES_DIR + "api/draft/")),
  ]);
}
gulp.task("wintersmith", function (done) {
  const wintersmith = require("wintersmith");
  const env = wintersmith("docs/config.json");
  env.build(GH_PAGES_DIR, function (error) {
    if (error) {
      done(error);
      return;