The previous version stated that it aimed to match the behavior of the
`query-string` package but it was actually tested against Node's
`querystring` package, which has slightly different behavior for this
edge case. It omits parameters with `undefined` values and renders empty
parameters for `null` values.

The notebook view was calling `api.search({ uri: undefined, ... })` and
this translated to `/api/search?uri=&...` which caused an error.

Omit parameters instead in this case.