Single-page PNG filename
When saving a single-page PNG file, the sequence "-1" is appended to the basename of the image. It would be useful in the case of a single-page file to remove "-1" which indicates the page that the image represents.
Untested, but when the number of pages in a file exceeds 10/100/1000, then it would be useful to prepend "0"'s to the page number in a .PNG export to make the digit count for all pages constant (2 digits for files with 99 or fewer pages, 3 digits for files with 999 or fewer pages, etc.).