HOWTO: Pagination SEO Markup (Correct canonical \ rel next \ rel prev markup)

tips & tricks
2

I think you must use the isset template function https://gohugo.io/templates/functions#isset

Something like this

 <link rel="canonical" href="{{ .Permalink }}">
    {{ if (isset .Paginator.HasPrev ) }}
      <link rel="prev" href="{{ .Paginator.Prev.URL  }}">
    {{ end }}