Using all ram

I am using the following function to try and create a thumbnail of a gif with a mask. icon.data is a buffer containing the gif data. The addMask function works with JIMP variables and works. even if I comment out the line that manipulates the frame it uses up all the ram and crashes with a FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory

```
let sourceGif=await codec.decodeGif(icon.data);
for (let i in sourceGif.frames) {
let frameImage = GifUtil.copyAsJimp(Jimp, sourceGif.frames[i]);
//frameImage=await addMask(frameImage,icon); //function that resizes a frame and adds a mask to the frame
sourceGif.frames[i]=new GifFrame(frameImage.bitmap);
}
GifUtil.quantizeDekker(sourceGif.frames, 256);

// The encoder determines GIF size from the frames, not the provided spec (sourceGif).
outputBuffer=codec.encodeGif(sourceGif.frames, sourceGif);

```

After some more checks I find that it is the GifUtil.quantizeDekker function causing the problem.