convert `nothing` and `missing`

[alex-s-gardner]

right now:

using GeometryBasics
import GeoInterface as GI

this errors

GI.convert(GeometryBasics, missing)

and this errors

GI.convert(GeometryBasics, nothing)

should they instead return missing and nothing respectively?

[rafaqz]

Maybe missing should as it's meant to propagate? But nothing wants handling

[asinghvi17]

Agreed, missing nothing should always error IMO. But we can build missing into GeoInterface (I think)?

Edited

[evetion]

Missing could be propagated, but doesn't really need to be imho. Convert takes something that is a geometry, if you pass in something else (say 1), you can expect a (method)error.