Improve error messaging when attempting to rotate multi-page image

[EjDadivas]

Possible bug

          sharp(await fileItem.toBuffer(), { animated: true })
          .resize(imgMaxWidth)
          .rotate(rotateVal)
          .toFormat("gif")
          .gif({
              loop: 0,
              force: true
          })
          .toFile(gifFileAssetPath, (err, info) => {
              console.log('### err GIF:', err)
              console.log('### info GIF:', info)
          })

When I try to rotate the GIF it only shows the first frame.

[lovell]

Rotation of multi-page (animated) images is unsupported. I thought I'd added logic to generate an error when this was attempted but I see it currently doesn't do so when the angle is 90 or 270, leading to unexpected output.

Commit cbf68c1 ensures an error is shown, adds more test cases and a note to the docs.

Thanks for reporting.

[lovell]

v0.33.2 now available with improved error messaging around this.

[EjDadivas]

Thank you