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)

describe("isBool", function () {
    it("handles boolean values", function () {
      expect(isBool(true)).toEqual(true);
      expect(isBool(false)).toEqual(true);
    });
    it("handles non-boolean values", function () {
      expect(isBool("true")).toEqual(false);
      expect(isBool("false")).toEqual(false);
      expect(isBool(1)).toEqual(false);
      expect(isBool(0)).toEqual(false);
      expect(isBool(null)).toEqual(false);
      expect(isBool(undefined)).toEqual(false);
    });
  });
  describe("isNum", function () {
    it("handles numeric values", function () {
      expect(isNum(1)).toEqual(true);
      expect(isNum(0)).toEqual(true);
      expect(isNum(-1)).toEqual(true);
      expect(isNum(1000000000000000000)).toEqual(true);
      expect(isNum(12.34)).toEqual(true);
    });
    it("handles non-numeric values", function () {
      expect(isNum("true")).toEqual(false);
      expect(isNum(true)).toEqual(false);
      expect(isNum(null)).toEqual(false);
      expect(isNum(undefined)).toEqual(false);
    });
  });
  describe("isString", function () {