Frame 1 uses more than 256 color indexes

Getting the above error trying to load and save a gif

```
return GifUtil.read(downloadedFile)
.then(inputGif =>
// Pass inputGif to write() to preserve the original GIF's specs.
GifUtil.write(outputFileName, inputGif.frames, inputGif))
```

Tried with a few gifs from the internet with same result. Can use quantize function but that causes massive distortion.