The error message implies that the reference to the template is on a line in three files. In fact it is in baseof.html.
ERROR render of "404" failed: execute of template failed: html/template:404.html:28:16: no such template "_internal/google_analytics_async.html"
ERROR render of "term" failed: execute of template failed: html/template:_default/list.html:28:16: no such template "_internal/google_analytics_async.html"
ERROR render of "page" failed: execute of template failed: html/template:_default/single.html:28:16: no such template "_internal/google_analytics_async.html"
Built in 107 ms
Error: error building site: render: failed to render pages: render of "page" failed: execute of template failed: html/template:_default/single.html:28:16: no such template "_internal/google_analytics_async.html"
I had to search to find it.
$ find . -name *.html -exec grep -Hi 'analytics' {} \;
./layouts/_default/baseof.html: {{ template "_internal/google_analytics_async.html" . }}
./themes/theme-hugo-foundation6/layouts/_default/baseof.html: {{ template "_internal/google_analytics_async.html" . }}