I agree with the Constructive Paranoia.

Being of an engineering mindset, I am even cautious when there is "no way" the data could be laid out incorrectly.

I've lost count of the number of times in my career my code has caught errors in an error-resistant environment, and handled it with some kind of grace (even yelling for help is more graceful than wandering off the edge of the Abyss in many cases), and I've had other folks asking how on earth I saw that coming. Simple: I didn't. I simply asked that most basic of engineering questions during the design phase: What could go wrong?

In an open-ended system such as this problem describes, Constructive Paranoia is absolutely warranted. I would almost say it is mandatory, but most folks have exceptions in their heads -- and, yes, Mike, it would not surprise me in the slightest if you were not amongst them :: grin ::.

The code can't react with judgement the way a human does (for better or for worse!). So you have to code all the edge and corner cases, and do your best to deal with the black hole cases as well. Otherwise, it will almost certainly come back to haunt you.