The prebuilt files include `web/pdf_viewer.js` with some viewer APIs. Those are missing from type declarations.
const viewerOutputName = "viewer.js";
  const viewerFileConfig = createWebpackConfig(
    defines,
    {
      filename: viewerOutputName,
    },
    {
      defaultPreferencesDir: options.defaultPreferencesDir,
    }
  );
  return gulp.src("./web/viewer.js").pipe(webpack2Stream(viewerFileConfig));
}
function createComponentsBundle(defines) {
  const componentsAMDName = "pdfjs-dist/web/pdf_viewer";
  const componentsOutputName = "pdf_viewer.js";
  const componentsFileConfig = createWebpackConfig(defines, {
    filename: componentsOutputName,
    library: componentsAMDName,
    libraryTarget: "umd",
    umdNamedDefine: true,
  });
  return gulp
    .src("./web/pdf_viewer.component.js")
    .pipe(webpack2Stream(componentsFileConfig))
    .pipe(replaceWebpackRequire())
    .pipe(replaceJSRootName(componentsAMDName, "pdfjsViewer"));
}
function createImageDecodersBundle(defines) {