Apple's developer.apple.com ships a classic BMP/DIB favicon.ico rather
than a PNG one, so the icon discovery that feeds the ZIM book icon found
nothing and the archive shipped without an Illustrator_48x48@1 image.
Decode the .ico container directly: read the directory, pick the largest
entry, and decode it either as the PNG a modern favicon embeds or as the
BITMAPINFOHEADER bitmap older ones still carry. The BMP path handles
32/24/8/4/1 bpp, the stacked AND transparency mask, and the all-zero
alpha case where a 32-bpp icon leans on the mask for its shape.
Tam Nguyen Duc
e576377359