Submitting an empty search returns results for 'undefined'

[kevinschaper]

Looking through Google Analytics, I noticed that our most popular search results page for 2020 was an empty search...which gives the embarrassing response of searching for the term 'undefined'

Some sites return an error message for an empty search, but I find that it's a nice opportunity to start browsing if I'm just getting a look around.

I wasn't sure if this was a UI or API issue, but it looks like might be a bit of both. The url requested by the UI begins with https://api.monarchinitiative.org/api/search/entity/undefined - so 'undefined' is coming from the UI code. Poking at it manually, the API url format doesn't seem to allow for an empty query string.

It would be nice to move both the UI urls and the API to using query or q as the query parameter. (This also has the side benefit of letting us configure site search Google Analytics)