Attach (recommended) or Link to PDF file here:
http://help.adobe.com/en_US/livecycle/11.0/SampleForms/941/Form.pdf

- Web browser and its version: Firefox 89.0.1
- Operating system and its version: Windows 10 10.0.19043.1052
- PDF.js version: commit bdfcdd6f8326f22c135edfa29a341ea4c558f3d1
- Is a browser extension: No

Steps to reproduce the problem:
1. Enable XFA support
2. Open form

What is the expected behavior? (add screenshot)
Page 3 (of 4) renders
![image](https://user-images.githubusercontent.com/7104454/122686842-622e9980-d1e1-11eb-92ab-86fe488560f2.png)

What went wrong? (add screenshot)
Only 3 pages total render in pdf.js
const DocumentInfoValidators = {
      Title: isString,
      Author: isString,
      Subject: isString,
      Keywords: isString,
      Creator: isString,
      Producer: isString,
      CreationDate: isString,
      ModDate: isString,
      Trapped: isName,
    };
    let version = this._version;
    if (
      typeof version !== "string" ||
      !PDF_HEADER_VERSION_REGEXP.test(version)
    ) {
      warn(`Invalid PDF header version number: ${version}`);
      version = null;
    }
    const docInfo = {