Surfaces missing when rendered with SolidModels, depending on MeshSized

[yfangad]

Some of the surfaces created using SolidModels.extrude_z!() are missing when rendered with SolidModels. Whether this problem occurs or not seems to depend on what MeshSized is used.
After modifying the following code in render! solidmodel/render.jl, changing remove_object=true to remove_object=false , the problem goes away and all the surfaces can be obtained.

        if isa(kernel(sm), OpenCascade)
            # Only OpenCascade supports boolean union.
            sm[h_name] = union_geom!(sm[h_name, 2], sm[h_name, 2], remove_object=true)
        end

[gpeairs]

Possibly related: in experimenting with this I've found that overlapping or adjoining extrusions are problematic in general, especially but not necessarily with MeshSized. Taking the union before extrusion helps but usually only without MeshSized.

[gpeairs]

#112 (now in v1.8.0) should fix the original issue. As noted, there may still be issues with overlapping extrusions without MeshSized physical groups, with a workaround of taking a union before extrusion.

[gpeairs]

The reordering from #145 should help preserve mappings in further cases. Closing this issue as resolved, we can open a new one if a related issue resurfaces.