The following code is flagged as dead (since it's *replacing* rather than updating the existing Object):
https://github.com/mozilla/pdf.js/blob/4483cba72410027acf46630ebf252ae529704476/src/core/xfa/template.js#L2336-L2339
according to the alert in https://github.com/mozilla/pdf.js/security/code-scanning/103?query=ref%3Arefs%2Fheads%2Fmaster

Looking at the surrounding code, I can see a couple of possibilities here:
 1. This is indeed just dead code, which should be removed.
 2. The code should be moved up, and placed just *above* the previous block instead.
 3. There should be other, more invasive, changes made to this code...

/cc @calixteman Which solution is correct here?
Assuming it's either option 1 or 2, I can submit a patch to fix this.
if (!this[$extra]) {
      const edges = this.edge.children.slice();
      if (edges.length < 4) {
        const defaultEdge = edges[edges.length - 1] || new Edge({});
        for (let i = edges.length; i < 4; i++) {
          edges.push(defaultEdge);
        }
      }
      const widths = edges.map(edge => edge.thickness);
      const insets = [0, 0, 0, 0];
      if (this.margin) {
        insets[0] = this.margin.topInset;
        insets[1] = this.margin.rightInset;
        insets[2] = this.margin.bottomInset;
        insets[3] = this.margin.leftInset;
      }
      this[$extra] = { widths, insets, edges };
    }
    return this[$extra];
  }
  [$toStyle]() {