Animated WebP's cannot actually be loaded

[SludgePhD]

WebPDecoder fails to decode WebP animations.

Expected

It should probably work?

Actual behaviour

• One file (piston.webp from the zip archive below) that works fine in Firefox and Chromium results in UnexpectedEof ("failed to fill whole buffer")
• Files from the image-webp test suite fail with "Format error decoding WebP: No more frames: No more frames"
  • https://github.com/image-rs/image-webp/tree/768b16b70b5a1d1315dda29ccc3777761a9b5a31/tests/images/animated

Reproduction steps

WebPDecoder::new(BufReader::new(File::open(path)?))?.into_frames().collect_frames()?

piston.zip