QueryStringAddon converts undefined values into empty strings instead of omitting them #229
Description
For a query like this
wretch('https://example.com').addon(QueryStringAddon).query({ bar: 'qwe', foo: undefined }).post().json();The produced URL is https://example.com?bar=qwe&foo= instead of https://example.com?bar=qwe