Shellcheck is truly a game-changer, even for people who've been hacking Bash (etc) for 20+ years.

Side note: it's also one of (or the ?) most popular Haskell projects out there: https://github.com/koalaman/shellcheck/

Pandoc might be more popular but I agree that Shellcheck is an absolute godsend.

Here here, this has massively improved my code to the point I no longer fear sh and what horrible things I have unleashed.