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.
oddOrEven: "odd",
      blankOrNotBlank: "nonBlank",
    };
    const root = this.subform.children[0];
    const pageAreas = root.pageSet.pageArea.children;
    const mainHtml = {
      name: "div",
      children: [],
    };
    let pageArea = null;
    let breakBefore = null;
    let breakBeforeTarget = null;
    if (root.breakBefore.children.length >= 1) {
      breakBefore = root.breakBefore.children[0];
      breakBeforeTarget = breakBefore.target;
    } else if (
      root.subform.children.length >= 1 &&
      root.subform.children[0].breakBefore.children.length >= 1
    ) {
      breakBefore = root.subform.children[0].breakBefore.children[0];
      breakBeforeTarget = breakBefore.target;
    } else if (root.break && root.break.beforeTarget) {
      breakBefore = root.break;
      breakBeforeTarget = breakBefore.beforeTarget;
    } else if (
      root.subform.children.length >= 1 &&
      root.subform.children[0].break &&
      root.subform.children[0].break.beforeTarget
    ) {
      breakBefore = root.subform.children[0].break;