search usability issue

[VladimirAlexiev]

Go to the search box ("535 endpoints"), type "getty", press enter rather than waiting & selecting from the autocomplete. It goes to http://sparqles.ai.wu.ac.at/endpoint? and reports
Service Unavailable: The server is temporarily unable to service your request due to maintenance downtime or capacity problems.

• if possible, enter should do the search and pick the first autocomplete result
• else, disable Enter on that form
• in either case, the error message should be more informative: "no results found" rather than the scary looking message above