This is an easy mistake to make, and miss when looking over your code. With hindsight - and having it explained to you - it is also a very easy mistake to under

This is an easy mistake to make, and miss when looking over your code. With hindsight - and having it explained to you - it is also a very easy mistake to understand. That doesn't mean it was an easy mistake to find. I bet it went without being detected for a long time.