Attach (recommended) or Link to PDF file here:
See pdf in https://github.com/mozilla/pdf.js/issues/3109

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: Windows 10
- PDF.js version: builtin viewer

Steps to reproduce the problem:
1. Look at outlines

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/141514798-0e656865-1cbf-4fb8-a89b-530d36da23c9.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/141514740-c95e0237-8bf4-4129-a4a5-cb2ea5a3f4df.png)

promise3,
      ]);
      expect(pageLabels[0]).toEqual(["i", "ii", "iii", "1"]);
      expect(pageLabels[1]).toEqual(["Front Page1"]);
      expect(pageLabels[2]).toEqual(["1", "2"]);
      expect(pageLabels[3]).toEqual(["X3"]);
      await Promise.all([
        loadingTask0.destroy(),
        loadingTask1.destroy(),
        loadingTask2.destroy(),
        loadingTask3.destroy(),
      ]);
    });
    it("gets default page layout", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );
      const pdfDoc = await loadingTask.promise;
      const pageLayout = await pdfDoc.getPageLayout();
      expect(pageLayout).toEqual("");
      await loadingTask.destroy();
    });
    it("gets non-default page layout", async function () {
      const pageLayout = await pdfDocument.getPageLayout();
      expect(pageLayout).toEqual("SinglePage");
    });
    it("gets default page mode", async function () {
      const loadingTask = getDocument(
        buildGetDocumentParams("tracemonkey.pdf")
      );