Attach (recommended) or Link to PDF file here:
[FormDB2_fr.pdf](https://github.com/mozilla/pdf.js/files/7352426/FormDB2_fr.pdf)

Configuration:
- Web browser and its version: Firefox nightly
- Operating system and its version: linux debian

Steps to reproduce the problem:
1. Open the pdf
2. The image on the top of each pages is missing 

What is the expected behavior? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465500-e8788893-f33d-4532-871d-43b464fa85f4.png)

What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/5641725/137465363-f2b35fe4-6776-45e9-b9e4-ccef6d9ad670.png)

if (this.subform.children.length === 0) {
      warn("XFA - No subforms in template node.");
    }
    if (this.subform.children.length >= 2) {
      warn("XFA - Several subforms in template node: please file a bug.");
    }
    this[$tabIndex] = DEFAULT_TAB_INDEX;
  }
  [$isSplittable]() {
    return true;
  }
  [$searchNode](expr, container) {
    if (expr.startsWith("#")) {
      
      return [this[$ids].get(expr.slice(1))];
    }
    return searchNode(this, container, expr, true, true);
  }
  [$toHTML]() {
    if (!this.subform.children.length) {
      return HTMLResult.success({
        name: "div",
        children: [],
      });
    }
    this[$extra] = {