boundary subgrids for 1D parent grid

[dilaraabdel]

I am struggling with ExtendableGrids and GridVisualize.

Suppose I have a 1D parent grid, e.g.

grid = simplexgrid([1,2,3])
sub = subgrid(grid,[2],boundary=true)

Then, the coordinates of sub are

julia> sub[Coordinates]
0×1 Matrix{Int64}

Everything works fine for a 2D parent grid. I see that this is due to this line where we take codimension 1 which is in the case of a 1D parent grid dimension 0.
I faced this problem when trying to visualize a 1D solution evaluated at the boundary with scalarplot() of GridVisualize.

Is this a "bad" thing to have boundary subgrids for a 1D parent grid or is this a bug?

[j-fu]

The question is what would be a good visualization of this. By point markers ? If there is an explainable canonical way, we could think about supporting zero-dimensional grids.