pert:
If you are making something that's intended for other people to use, then you do need to think about those edge cases.
Several times I have shown some new program to a friend of mine who is very intelligent but not interested in computers and each time he has done something within 2 minutes that has broken the program.
What he did was perfectly reasonable, it was just something it would never have occurred to me to do.
Maybe, as the author, I subconsciously knew not to do that thing?
You can't make anything foolproof because fools are too clever.
...R