Don't feel stupid, we all make simple mistakes ;)

As far as an IDE catching these issues, you don't need one. Your original error stated exactly what you needed to know... I have never used an IDE (just vi/vim) up until recently. On my home Mint Linux laptop, I've started using IntelliJ with the IdeaVim and Camelcade (Perl5) plugins. Works very well. I use PyCharm at work, so I figured having similar IDEs for my Python coding and Perl coding would be handy... it is.