Attach (recommended) or Link to PDF file here:
PDF from #4106, https://mail.gnome.org/archives/evince-list/2013-November/pdfNC0hkVW67a.pdf.

Steps to reproduce the problem:
1. Open the PDF

What is the expected behavior?
![immagine](https://user-images.githubusercontent.com/1616846/121865567-67ca4200-ccfe-11eb-8673-1d6e863fc8d5.png)

What went wrong?
The PDF doesn't load, `TypeError: can't access property Symbol(), match is null` error is logged in the console.
return (
      this.hasOwnProperty(value[$nodeName]) &&
      this[value[$nodeName]].children.some(
        node => node[$content] === value[$content]
      )
    );
  }
  [$toHTML]() {
    const output = [];
    for (const child of this[$getChildren]()) {
      output.push(child[$text]());
    }
    return HTMLResult.success(output);
  }
}
class Keep extends XFAObject {
  constructor(attributes) {
    super(TEMPLATE_NS_ID, "keep",  true);
    this.id = attributes.id || "";
    const options = ["none", "contentArea", "pageArea"];
    this.intact = getStringOption(attributes.intact, options);
    this.next = getStringOption(attributes.next, options);
    this.previous = getStringOption(attributes.previous, options);
    this.use = attributes.use || "";
    this.usehref = attributes.usehref || "";
    this.extras = null;
  }
}
class KeyUsage extends XFAObject {