`init` being used in applyreduce when I don't think it should

[asinghvi17]

using GADM
import GeoInterface as GI, GeometryOps as GO
texas = GADM.get("USA", "Texas") |> GI.getfeature |> only |> GI.geometry
texas_lower = GO.applyreduce(vcat, GO.TraitTarget(GI.AbstractCurveTrait), texas) do geom
    points = GO.forcexyz(geom, 0.0).geom
    push!(points, (NaN, NaN, NaN))
    return points
end

114424-element Vector{Union{Nothing, Tuple{Float64, Float64, Float64}}}:
 nothing
 nothing
 (-97.27569599999993, 26.237083000000098, 0.0)
 (-97.27541399999996, 26.237083000000098, 0.0)
 (-97.27541399999996, 26.236528000000135, 0.0)
 (-97.27513899999997, 26.236528000000135, 0.0)
 (-97.27513899999997, 26.235695000000135, 0.0)
 ⋮
 (-97.13500199999987, 28.056389000000024, 0.0)
 (-97.1347199999999, 28.056667000000118, 0.0)
 (-97.13444499999997, 28.056667000000118, 0.0)
 (-97.13416299999989, 28.056944000000158, 0.0)
 (-97.13333099999988, 28.056944000000158, 0.0)
 (NaN, NaN, NaN)

That returns a vector where the first 2 elements are nothing, the rest are as expected. But it's all a bit odd really. We ought to not put those nothings in.

Passing init = (NaN, NaN, NaN) to applyreduce fixes it for now...but this is the kind of thing we should just do without needing init.

[asinghvi17]

Another weird issue: if init is a Makie.Point3d, somehow it gets splatted out into three float64s in the output. That's probably because it's being passed to vcat and somehow the tuple is accepted correctly whereas the Point3d is a vector, so not really anyone's fault per se

[asinghvi17]

This will take some thought. maybe we have to be a bit smarter about this and somehow construct an iterator rather than just doing the recursion. I have a feeling this happens because:

• you recurse into a vector of polygons
• each polygon has one ring
• you run mapreduce a bunch of times with only a single item in the collection

So maybe it has to be more like flatten really. This is where an explicit stack would be really handy...but very difficult to do without a "single source of truth" geometry type to rely on