"Expected group end" on valid LineString

[Portur]

Hi,
This LineString

LINESTRING(18.6233900000 -33.8963590000 0, 18.6234010000 -33.8966330000 0, 18.6234090000 -33.8967650000 0, 18.6234420000 -33.8973360000 0, 18.6234490000 -33.8974650000 0, 18.6234790000 -33.8980180000 0, 18.6234860000 -33.8981470000 0, 18.6235040000 -33.8985640000 0)

used like this

let feature = {
      type: 'Feature',
      properties: {},
      geometry: wkx.Geometry.parse(linestring).toGeoJSON()
};

throws this
"Expected group end"

Is it a 3D issue?
Viewing the linestring in WKT view does display correctly