Right on, Bart! I've been programming, or I should say humiliated, for 50 years now. In the early days it was fairly common to find a bug in the compiler, after we moved beyond machine languages. I usually start with the last change I made. When I didn't find it immediately I remembered the recent upgrade. Humiliated again! But you quickly put me on the right track.
I try to keep the proper perspective by recalling that an engineering geometry program of mine ran for nine years every working day until it finally hit one line of code that caused a divide by zero overflow. It makes me shudder when I think of computers running flight and military ordnance software.
Gary