Attach (recommended) or Link to PDF file here:
issue13500 (in test corpus)

This regressed when landing #13566. 

What is the expected behavior? (add screenshot)
<img width="664" alt="image" src="https://user-images.githubusercontent.com/942640/122467522-7bc8aa80-cf6f-11eb-9d4d-311eb7c64fb2.png">


What went wrong? (add screenshot)
![image](https://user-images.githubusercontent.com/942640/122467565-85eaa900-cf6f-11eb-9c10-8a8686ed440c.png)


};
    const root = this.subform.children[0];
    root.pageSet[$cleanPage]();
    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;
      breakBeforeTarget = breakBefore.beforeTarget;