ShellCheck is a GPLv3 tool that provides warnings and possible suggestions for bash/sh shell scripts. ShellCheck finds bugs in your shell scripts. You can cabal, apt, dnf, pkg or brew install it locally right now. ShellCheck highlights and clarifies typical beginner's syntax mistakes and issues that cause a shell to give a cryptic error message. It shows typical intermediate level semantic problems that cause a shell to behave in a abnormally and counter-intuitively.
...The easiest option to get pandoc-crossref on Windows, macOS, or Linux, is to download pre-built executables available at the releases page. Bear in mind that those are a product of automated build scripts, and as such, provided as-is, with zero guarantees. Feel free to open issues if those don't work though, I'll try to do what I can.