missing value => string for several types

[cdriesler]

https://twitter.com/secretlyagoblin/status/1390855265344311296?s=20

unforced error, totally forgot about this. although the compute server will solve things whether or not the client knows how to handle values/type (i.e. vectors), it will still deliver the values and the client doesn't know how to show them

implement type handling explicitly so the data tooltip will show useful info

• Vector
• Boolean