I've never been able to find a way to be warm/positive/supportive/encouraging/empathic while also impressing on someone that their screwup might have cost the company six+ figures. Or worse - in some contexts, consequences can be kinetic.
Blood baths are not acceptable, but positivity is not always capable of effectively communicating consequences. Positivity works best when very little explaining of mistakes is required.
Sometimes an empathetic explanation that something should be better will suffice. Sometimes you encounter "It works, it's fine", and something more than empathy is required.
If code has gotten out into the wild and has cost a company six+ figures, that developer is _not_ the company's biggest problem and it's not all his/her fault.
You'd be surprised. Some companies give individual devs a lot of autonomy.
My point is that positivity and empathy works best when people already know they've screwed up. Otherwise, you have to explain how they erred, what the consequences were/are, and how to fix it. The first two are more difficult to do in a positive way.
Blood baths are not acceptable, but positivity is not always capable of effectively communicating consequences. Positivity works best when very little explaining of mistakes is required.
Sometimes an empathetic explanation that something should be better will suffice. Sometimes you encounter "It works, it's fine", and something more than empathy is required.