A PL/SQL RAISE_APPLICATION_ERROR (ORA-20000 to ORA-20999): its number
and message, without the ORA-20xxx: prefix and the ORA-06512 stack
lines. Its code is CONFLICT (409), and the message is for the client.
The database's or the driver's code: 'ORA-00001', 'NJS-040', 'NJS-123'…
The ORA error number of the failure, if the database reported one.
Whether web-kit shows the message to the client: a PL/SQL application error's.
The statement ran out of time: node-oracledb's callTimeout (NJS-123) or the driver's deadline.
one()found no row:NOT_FOUND, which web-kit answers with a 404.