FIX: ensure the post url is present

Also don't interpolate a string

plugins/poll/plugin.rb

@@ -438,9 +438,9 @@ after_initialize do
   on(:reduce_excerpt) do |doc, options|
     post = options[:post]
 
-    replacement = post ?
+    replacement = post&.url.present? ?
       "<a href='#{UrlHelper.escape_uri(post.url)}'>#{I18n.t("poll.poll")}</a>" :
-      "#{I18n.t("poll.poll")}"
+      I18n.t("poll.poll")
 
     doc.css("div.poll").each do |poll|
       poll.replace(replacement)