The code that tests for defined is in the section on CAVEAT/limitations

No, every single fork example in perlipc shows the defined check too, and of course it's documented in fork itself.

perlipc is a more advanced set of functionality ... I will certainly consider the possibility of undef for more complex multiforking situations, but that hardly justifies raising it for this case

It's much simpler than that: the system may not support fork, may be out of resources, etc. Are you certain that on the OP's system, or any system that their code might be run on in the future, fork will never ever return undef under any circumstances?

inhibit learning as well as disrupting the purpose of SOPW

You seem to be advocating "don't check the operation for errors" - do you really think that's a good idea?

Frankly these "contributions" are a sign of ego problems 'I know something too -- look at me!'

That could be said about many replies to many questions here - yours, mine, and just about everyone else's. Sorry, but that's a silly non-insult.