Heatmap coloring boxes that should be empty

[jariji]

I expected the ! facet m row to be empty but it has colored boxes without text. There is also something strange going on with the tick alignment around there.

let
  n = 1000
  df = DataFrame(x=rand('A':'Z',n), y=rand('a':'z',n), z=rand(1:1000,n), c=rand('!':'%',n))
  d = combine(groupby(df, [:x,:y,:c]), :z => sum)
  # Remove values for one facet and row.
  subset!(d, [:x,:y,:c,:z_sum] => ByRow((x,y,c,z)-> !((c == '!') && (y == 'm'))))
  ll = (
      data(d)
      * mapping(:x,:y; layout=:c)
      * (
          visual(Heatmap) * mapping(:z_sum)
          + visual(Makie.Text; align=(:center,:center), color=:red) * mapping(text=:z_sum=>verbatim∘string)
        )
  )
  draw(ll; figure=(;resolution=(3000,2000)))
end

[cbdf2221] AlgebraOfGraphics v0.6.8
[13f3f980] CairoMakie v0.8.6
[ee78f7c6] Makie v0.17.6
julia 1.7.1

[piever]

What's happening IMO is the following. Makie sees a gap in the axis (from l to n, which has been automatically translated to integers by AoG) and is expanding the boxes to fill in the gap. A simpler MWE would be

using CairoMakie
heatmap([1, 2, 4, 5], [1, 2, 3, 4], rand(4))

The conversion is happening here. This should probably be fixed on the Makie side first. Maybe one could allow an optional width argument to heatmap to help compute correct edges?