Let's say you write a program that, when started, reads its configuration file to know which modules to start-up etc. If that configuration file is missing, an error will probably show up. This is an important situation that must always be handled.
I read a statistic once which said that about 70 % of the code in a typical program is there to deal with corner cases (like check that file is not missing, catch an Exception, check that I don't divide by 0, check that a person's age is a positive number etc.).
I don't believe this (i.e. the 70 % claim) to be very accurate, but then again, a lot of the code that I write contains a lot of
ifs that check for valid parameters and stuff like that. I doubt I'm the only one who does this. So that statistic does have some truth in it.
If a big part of a program's code is represented by these checks, then shouldn't these cases be represented in UML diagrams ? (like sequence diagrams etc.). I can't remember if I ever saw such things.
Should I include them in my diagrams ? Will that enlighten or disturb/confuse another programmer who looks at those diagrams ? Would the diagrams then become too big because of this ?