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.
const style = toStyle(this, "font", "margin", "para", "visibility");
    switch (this.placement) {
      case "left":
      case "right":
        if (this.reserve > 0) {
          style.width = measureToString(this.reserve);
        } else {
          style.minWidth = measureToString(this.reserve);
        }
        break;
      case "top":
      case "bottom":
        if (this.reserve > 0) {
          style.height = measureToString(this.reserve);
        } else {
          style.minHeight = measureToString(this.reserve);
        }
        break;
    }
    return HTMLResult.success({
      name: "div",
      attributes: {
        style,
        class: ["xfaCaption"],
      },
      children,
    });
  }
}
class Certificate extends StringObject {