Use .presence instead of ternary on site description for og: content (#2033)

app/views/about/show.html.haml

@@ -8,7 +8,7 @@
   %meta{ property: 'og:site_name', content: site_title }/
   %meta{ property: 'og:type', content: 'website' }/
   %meta{ property: 'og:title', content: Rails.configuration.x.local_domain }/
-  %meta{ property: 'og:description', content: strip_tags(@instance_presenter.site_description.blank? ? t('about.about_mastodon') : @instance_presenter.site_description) }/
+  %meta{ property: 'og:description', content: strip_tags(@instance_presenter.site_description.presence || t('about.about_mastodon')) }/
   %meta{ property: 'og:image', content: asset_url('mastodon_small.jpg') }/
   %meta{ property: 'og:image:width', content: '400' }/
   %meta{ property: 'og:image:height', content: '400' }/