using bad database name should throw human readable error message

[NovemLinguae]

Steps to reproduce

• https://sql-optimizer.toolforge.org/
• type mediawikiwiki for the database name, omitting the _p
• type something simple for the query, like SELECT * FROM page
• submit

What happens?

• {"statusCode":500,"error":"Internal Server Error","message":"An internal server error occurred"}

What should have happened?

• A human readable error such as "Bad database name", preferably inserted into the current page rather than its own page