Swiss cheese
Single line of code... Very possible.
I have 12 years experience as a performance test engineer and the combination of factors times volume is what I try to replicate when testing.
It looks like one combination of many mi!llions didnt, work.
I'm sorry someone didn't find it in testing but did anyone die?
It looks like a great result except I wonder what a comparison group looks like...
How often do they fail... There is your answer....