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)


for (const page of this.pageArea.children) {
      page[$cleanPage]();
    }
    for (const page of this.pageSet.children) {
      page[$cleanPage]();
    }
  }
  [$isUsable]() {
    return (
      !this.occur ||
      this.occur.max === -1 ||
      this[$extra].numberOfUse < this.occur.max
    );
  }
  [$getNextPage]() {