fix: head.html: WARNING: calling IsSet with unsupported type "invalid" (<nil>) will always return false.

Author: ttys3

layouts/partials/head.html

@@ -27,7 +27,7 @@
 
 <!-- Twitter Card -->
 <meta name="twitter:card" content="summary" />
-{{ if (isset $.Site.Params.Twitter "site") }}
+{{ with $.Site.Params.Twitter.site }}
   <meta name="twitter:site" content="{{ $.Site.Params.Twitter.site }}" />
 {{ end }}
 <meta name="twitter:creator" content="{{ if .IsHome }}{{ $.Site.Params.Twitter.creator }}{{ else if isset .Params "authortwitter" }}{{ .Params.authorTwitter }}{{ else }}{{ .Params.Author }}{{ end }}" />