hmc-guide/themes/hugo-mod-jslibs-dist/popperjs/README.md

[[module.imports]]
path="github.com/gohugoio/hugo-mod-jslibs-dist/popperjs/v2"

With that you can import it in your JS like this:

import * as Popper from "@popperjs/core";

Note that this module was originally added for https://github.com/gohugoio/hugo-mod-bootstrap-scss