Changes to error handling for background worker initialization?

I have an extension that uses background workers.  I pass a database oid as an argument in order to launch the worker using function BackgroundWorkerInitializeConnectionByOid.  In one of my regression tests that was written, I intentionally launch the worker with an invalid oid.  In earlier PG versions the worker would successfully launch but then terminate asynchronously, with a message in the server log.  Now, it does not even successfully launch but immediately errors (hence failing my regression tests).

I have recently installed all later point releases of all versions 9.5-11, so I assume this is due to some code change.  The behavior seems reasonable but I don't find any obvious release notes indicating a patch that would have changed this behavior.  Any thoughts?

Thanks,
Jeremy