Concat error when bundling js files from theme

[brokenindexfinger]

I’m attempting to bundle some JS assets, following the example from the docs here: https://gohugo.io/hugo-pipes/bundling/

I’m getting the following error: error calling Concat: slice []interface {} not supported in concat. Here’s the relevant code in my partial.

{{ $jquery := resources.Get "js/lib/jquery.min.js" }}
{{ $anime := resources.Get "js/lib/anime.min.js" }}
{{ if eq .Site.Params.includeBootstrapJs true }} }}
  {{ $bootstrap := resources.Get "js/lib/bootstrap.bundle.min.js" }}
  {{ $js := slice $jquery $bootstrap $anime | resources.Concat "js/bundle.js" }}
{{ else }}
  {{ $js := slice $jquery $anime | resources.Concat "js/bundle.js" }}
{{ end }}
<script src="{{ "js/bundle.js" | relURL }}"></script>

The assets in question are located in /themes/hugo-base-theme/static/js/lib/.

I’ve had a look at this issue and not able to understand how the solution there would apply to my use case.

Relevant changes are in this diff.

[brokenindexfinger]

I’m able to get it working, but only by moving the JS files from the theme to ./assets. Is there any way around that? We have several hugo projects and we like to simply move the relevant theme files when starting a new project.

[brokenindexfinger]

It looks like the site setting assetDir will work when pointed to a dir in the theme, despite some commentary in the git repo that (maybe) suggests otherwise…