Error: can't evaluate variable Site

I would like to set links in my sidebar menu to a Taxonomy list with the same value in the Taxonomy “catalog” as the key for the current Taxonomy, like so:

{{ range $taxonomyname, $taxonomy := .Site.Taxonomies }}
        <li> 
        <a href="#">&#x02022; {{ humanize $taxonomyname | title }} <span class="fa arrow"></span></a>
            <ul class="nav nav-second-level">
        
        {{ range $key, $value := $taxonomy }}
                
                                <li>
                                    <a href="#">&#x000B7; {{ title $key }} <span class="fa arrow"></span></a>
                                    <ul class="nav nav-third-level">
                                        {{ if in .Site.Taxonomies.catalog $key }}    <- THIS is what's giving me problems
                                        <li hugo-nav="/catalog/{{ $key }}/"><a href="/catalog/{{ $key }}/">&#x022C5; Catalog</a> </li>
                                        {{ end }}
                                        {{ range $value.Pages }}
                                        <li hugo-nav="{{ .RelPermalink}}"><a href="{{ .Permalink}}">&#x022C5; {{ title .LinkTitle }} </a>  </li>
                                        {{ end }}
                                    </ul>
                                    <!-- /.nav-third-level -->
                                </li>
                
        {{ end }}
                
        </ul>
        {{ end }}
            </li>

It works fine if I do not wrap the link to the catalog in the template function, but without the template function, every key gets a link to a Taxonomy list within catalog, even if there is no list and I get a 404 error. I only want there to be a link if there is a catalog member with the same value as the current key. Right now, I get an error that reads, “can’t evaluate variable Site.” This seems like it should work to me, and nothing else I have found has worked. Please help.

When you enter a loop in a Go template, the context changes. Try using $.Site.