That change won't be equivalent to the old check.

If we drop the `!aResult` check, then the new callback function would save the image, instead a no-op like the old one.
I wanted to negate the original condition, and this seemed a little bit shorter than the original negation below.

So I could even change this to `aResult !== fp.returnOK && aResult !== fp.returnReplace` to avoid confusion.

Uhh. There is a typo: `returnCancel` is undefined! I wanted to use `fp.returnCancel`.

Should I use the long form to avoid confusion, or just update the typo?