group clip raster can not save as base64Data

[the-didi]

Description/Steps to reproduce

1. create an new raster with base64 string
2. create an new path with some points on the raster that just create
3. create an new group that contains the raster and the path
4. set the group clipMask equlas to true
5. set the raster clipMask equals to true
6. then i got an new group that cliped an raster,but i dont know is there an way to export dataUrl of this raster

Additional information

// please ignore it,it just for get an newPath
const newPath = path.subtract(origin)
// set properties of the newPath
newPath.fillColor = new paper.Color(255, 0, 0)
newPath.fillColor.alpha = 0.5
newPath.selected = true
image.crossOrigin = 'anonymous'
// set raset clipMask equals to true
image.clipMask = true
// create an Group
const group = new paper.Group()
// set group clipMask
group.clipMask = true
// clip the raster
group.addChild(newPath)
group.addChild(image)
 group.selected=  true

....

// then how could i get the dataUrl of the raster that i just cliped?