Maybe if you'd read the third paragraph in Not_a_Number's reply:

Scrolling down to the bottom, your last three subs try to use a non-existent global @LINE array, a problem which of course strictures would have identified.

you'd have worked out for yourself exactly how the advice might have helped the OP? To use strictures is never bad advice, and often enough strictures are all that is needed to highlight the actual problem.

Advising people to use strictures is somewhat akin to the advice "fix the first error first". Strictures may not always identify the root problem. But very often they aid in eliminating a whole bunch of silly errors that distract from the root problem.

Conventional wisdom is none the worse for being conventional. It's unfortunate that so many people have to be reminded of it however.