charts with custom images lose those images when composed with other charts

[schanzer]

The following code works as-expected:

image-scatter-plot :: (t :: Table, xs :: String, ys :: String, f :: (Row -> Image)) -> Image
fun image-scatter-plot(t, xs, ys, f) block:
  images = t.all-rows().map(f)
  render-charts([list: 
          from-list.image-scatter-plot(images, ensure-numbers(t.column(xs)), ensure-numbers(t.column(ys)))])
    .x-axis(xs)
    .y-axis(ys)
    .display()
end

test = table: x,y
  row: 1,2
  row: 10, 20
end

image-scatter-plot(test, "x","y", lam(r): triangle(15, "solid", "red") end)

(Note that I'm using render-charts on purpose in this example. The real code just uses render-chart.)

Now change the render-charts line to add a function plot:

  render-charts([list:
       from-list.function-plot(num-sqr), 
       from-list.image-scatter-plot(images, ensure-numbers(t.column(xs)), ensure-numbers(t.column(ys)))])

And the custom triangles disappear.

I don't see any JS errors in the console either, and re-arranging the order of the dataseries in the list has no impact.