I was getting time to time "non-transient entity has a null id" AssertionFailure in EntityType.replace() when trying to persist an entity via EntityManager.merge().
Such message doesn't give much clue about exact entity which caused the problem - there can be quite a lot cascaded updates.
And I can't use debugger because the problem is floating - it happens in less then 10% of cases on cloud enviromnent.

So I would greatly appreciate if this error message contained more information - at least name of entity which caused problem. Ideally also it's parent entity or the whole entities path which led to this exception.

Thanks!