It often isn't as simple as using a correlation identifier and looking at logs across the service infrastructure. If you have a misconfiguration or hardware issue it very likely may be intermittent and only visible as an error in a log before or after the request. The response has incorrect data inside a properly formatted envelope.
I guess that's one of the advantages of serverless - by definition there can be no unrelated error in the state beyond the request (because there is none), except for the infrastructure definition itself. But a misconfig there you'll always see in form of an error happening at calling the particular resource - at least I haven't seen anything else yet.
