Firefox Cannot Save or Load Files

[RyanR712]

Describe the bug
Neither CTRL+S or clicking the save button on Firefox download files. There is no difference in behavior between Draw Mode and Proof Mode downloads.

CTRL+S will attempt to download the .webp file and clicking the save file button will bring up a 404 error.

To Reproduce
Access PMH via Firefox. Then,

Create some drawing or some proof and attempt to save it through CTRL+S or clicking the save button.

In the former case, you will download a .webp file instead.

In the latter case, you will get redirected to a 404 error.

Expected behavior
CTRL+S and clicking the save button should prompt the user to download a .json file to their downloads folder.

Screenshots Or Video
Improper CTRL+S behavior.

Improper save button behavior.

[James-Oswald]

Cause: Firefox does not have "showSaveFilePicker" https://developer.mozilla.org/en-US/docs/Web/API/Window/showSaveFilePicker

This triggers quick download code, which behaves differently on Firefox, as clicking a link opens a new tab rather than starting a download.

const f = document.createElement("a");
f.href = aegStringify(data);
f.download = name + ".json";
f.click();

[James-Oswald]

Bug also applies to loading files