GeoJSON writer should not write null coordinates

[caspervdw]

The GeoJSON writer writes NaN coordinates to null.

>>> pygeos.to_geojson(pygeos.Geometry("LINESTRING (1 nan, 2 2)"))
'{"type":"LineString","coordinates":[[1.0,null],[2.0,2.0]]}'

The inverse operation however does not work:

>>> pygeos.from_geojson('{"type":"LineString","coordinates":[[1.0,null],[2.0,2.0]]}')
GEOSException: ParseException: Error parsing JSON: '[json.exception.type_error.302] type must be number, but is null'

There is a lot to say about allowing nan coordinates at all, but as they are allowed now and the writer handles them properly, I would expect the reader handles them as well.

[rouault]

The issue is not on the reader, but on the writer. A null member in the coordinate array is illegal. ​https://datatracker.ietf.org/doc/html/rfc7946#section-3.1.1 : "A position is an array of numbers"