[WIP] Setup null type
[WIP] Setup null type

Haven't tested since I don't have TS 2.0 locally yet!

vega/vega-lite,vega/vega-lite,uwdata/vega-lite,vega/vega-lite,vega/vega-lite,uwdata/vega-lite,uwdata/vega-lite,uwdata/vega-lite,vega/vega-lite,uwdata/vega-lite