Attach (recommended) or Link to PDF file here:
[Scan-to-Mail-PDF1_(1).pdf](https://github.com/mozilla/pdf.js/files/6876708/Scan-to-Mail-PDF1_.1.pdf)

Configuration:
- Web browser and its version: Firefox Developer 91.0b7 (64-Bit)
- Operating system and its version: Windows 10 (21H1)
- PDF.js version: 2.10.339 (also tested with the online demo, Version 2.11.5)
- Is a browser extension:

Steps to reproduce the problem:
1. Open the attached pdf
2. Scroll to page 3

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/7944797/126957487-cc7a2d19-adfb-42e4-9809-74e1a7a85048.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/7944797/126957351-29aebb4d-eadd-4273-b69d-530b9060c12c.png)




const readableStream = this.streamTextContent(params);
    return new Promise(function (resolve, reject) {
      function pump() {
        reader.read().then(function ({ value, done }) {
          if (done) {
            resolve(textContent);
            return;
          }
          Object.assign(textContent.styles, value.styles);
          textContent.items.push(...value.items);
          pump();
        }, reject);
      }
      const reader = readableStream.getReader();
      const textContent = {
        items: [],
        styles: Object.create(null),
      };
      pump();
    });
  }
  /**
   * @returns {Promise<StructTreeNode>} A promise that is resolved with a
   *   {@link StructTreeNode} object that represents the page's structure tree,
   *   or `null` when no structure tree is present for the current page.
   */
  getStructTree() {