Attach (recommended) or Link to PDF file here:
[0 NIF MODELO 30.pdf](https://github.com/mozilla/pdf.js/files/7187486/0.NIF.MODELO.30.2.pdf)

Configuration:
- Web browser and its version: firefox nightly
- Operating system and its version: linux debian

Steps to reproduce the problem:
1. Open the PDF
2. Click on the button  `Rellenar Formulario` (top right of the first page)
3. There is the pop-up "Stay... or Leave...`.

It's a bit annoying from the user pov and it doesn't make sense (nobody wants to leave the form but just reset it)

It works fine when replacing  `""` by `"#"` here:
https://github.com/mozilla/pdf.js/blob/7082ff9bf876b98fbda118cdbd6267d3c0df6948/src/display/annotation_layer.js#L483

@Snuffleupagus, you changed this few month ago:
https://github.com/mozilla/pdf.js/commit/e2b6d79dee9ffd2aba715d6b3cb8fa143d86153c

do you have some ideas ?
while (selectElement.length !== 0) {
              selectElement.remove(0);
            }
            storage.setValue(id, { value: null, items: [] });
          },
          insert(event) {
            const { index, displayValue, exportValue } = event.detail.insert;
            const optionElement = document.createElement("option");
            optionElement.textContent = displayValue;
            optionElement.value = exportValue;
            selectElement.insertBefore(
              optionElement,
              selectElement.children[index]
            );
            storage.setValue(id, {
              value: getValue(event,  true),
              items: getItems(event),
            });
          },
          items(event) {