The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
const workerAMDName = "pdfjs-dist/build/pdf.worker";
  const workerOutputName = "pdf.worker.js";
  const workerFileConfig = createWebpackConfig(defines, {
    filename: workerOutputName,
    library: workerAMDName,
    libraryTarget: "umd",
    umdNamedDefine: true,
  });
  return gulp
    .src("./src/pdf.worker.js")
    .pipe(webpack2Stream(workerFileConfig))
    .pipe(replaceWebpackRequire())
    .pipe(replaceJSRootName(workerAMDName, "pdfjsWorker"));
}
function createWebBundle(defines, options) {