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)


if (this.subform.children.length === 0) {
      warn("XFA - No subforms in template node.");
    }
    if (this.subform.children.length >= 2) {
      warn("XFA - Several subforms in template node: please file a bug.");
    }
  }
  [$searchNode](expr, container) {
    if (expr.startsWith("#")) {
      
      return [this[$ids].get(expr.slice(1))];
    }
    return searchNode(this, container, expr, true, true);
  }
  [$toHTML]() {
    if (!this.subform.children.length) {
      return HTMLResult.success({
        name: "div",
        children: [],
      });
    }
    this[$extra] = {
      overflowNode: null,
      pageNumber: 1,
      pagePosition: "first",
      oddOrEven: "odd",
      blankOrNotBlank: "nonBlank",