No data in the specified time range results in 500 error instead of "No Data" message

In the public SOCAT LAS, a user restricted the time range to just 1 May 2019 -31 May 2019, but in V2019 there is no data after Feb 2019.  (The LAS is configured to allow all dates of 2019 so that selecting year 2019 doesn't auto-change the month.)  Rather than getting the "No Data Found" plot, a server returned a http status 500.
