Integer Overflow Errors
Using an unsigned variable in a computer program can lead to unexpected errors which we call overflow errors.
This is where if we subtract one from the variable when it is 0 it becomes an unexpectedly large number like 4294967295.
This is a problem we can see in Iguana 6.1 which is relatively harmless although alarming looking.
But it’s also the same problem that caused the French Ariane rocket to explode (a $500 million dollar disaster - see The number glitch that can lead to catastrophe).
Google around and you’ll find all sorts of expensive problems that arise from this issue.
How does it happen? Read about how computers handle subtraction.