sharp - creating an image to overlayWith different buffers at specific offsets

[afullstopdot]

Why does a sharp object not have persistence, I make a point to overlay each row of pixels and save the final image in the end but toFile() only creates an image with the last position I tried to overLay. Am I using overlayWith incorrectly or is that just the way it has been created. I cant find any information about this.

image.metadata().then((metadata) => {
        return {
            width: metadata.width,
            height: metadata.height,
            channels: metadata.channels
        }
    })
    .then((metadata) => {

        /*
        ** Tiles are 20x20 modulo for less computation
        */

        var xMax = metadata.width - (metadata.width % 20)
        var yMax = metadata.height - (metadata.height % 20)
        let final = sharp({
            create: {
                width: xMax,
                height: yMax,
                channels: metadata.channels,
                background: { r: 255, g: 255, b: 255 }
            }
        })
        .jpeg()

        /*
        ** Loop through x-axis
        */

        for (let xOffset = 0; xOffset <= xMax; xOffset += 20)
        {

            /*
            ** Loop through y-axis
            */

            for (let yOffset = 0; yOffset <= yMax; yOffset += 20)
            {

                /*
                ** To prevent a read biigger then possible
                */

                if ((yOffset + 20) > metadata.height || (xOffset + 20) > metadata.width)
                    break ;

                /*
                ** Extract the 20x20 tile from the input image
                */

                image.clone().extract({
                    left: xOffset,
                    top: yOffset,
                    width: 20,
                    height: 20
                })
                .toBuffer()
                .then((buffer) => {

                    /*
                    ** Get the color distance of the 20x20 tile
                    */

                    return  color.distance(buffer)
                    .then((space) => { return space.space })
                    .catch((err) => console.log(err))
                })
                .then((space) => {

                    /*
                    ** Find the image in the db with the smallest difference
                    */

                    return distance.smallest(db, space)
                })
                .then((path) => {

                    /*
                    ** Resize the image from the db with smallest difference
                    */

                    return sharp(path).resize(20, 20).toBuffer()
                })
                .then((buffer) => {

                    /*
                    ** Insert resized image into 20x20 tile
                    */

                    final.overlayWith(buffer, {
                        top: yOffset,
                        left: xOffset
                    })
                })
                .catch((err) => console.log(err))

            }
        }

        // final.toFile('./output/' + Date.now() + '.jpg')

    })
    .catch((err) => console.log(err))

[lovell]

Hello, please see #728