Fix double sourceCouldNotFindRecords invocation
Fix double sourceCouldNotFindRecords invocation

Sample case where this bit us: jmap-js where you have two fetchers for
the same record (the message, then the message details), and request
both. The first would change the status from EMPTY to NON_EXISTENT, but
then the second would change it from NON_EXISTENT to DESTROYED rather
than leaving it at NON_EXISTENT as it should.

fastmail/overture