Also cache non-existing to reuse it

[nickvergessen]

Strips of a query per OCS request in my integration test runs.

Screenshot of the query log. The yellow one is the entry where we now cache the exception additionally

[PVince81]

👍

though, using null or false might use less memory and be more intuitive than storing an exception

[nickvergessen]

though, using null or false might use less memory and be more intuitive than storing an exception

But then we can not rethrow the previous exception and I did not want to go and check all places if something depends on the parent exception

[nickvergessen]

/backport to stable23

[nickvergessen]

/backport to stable22