check if the link exists, redirects home if it doesn't

app.rb

@@ -18,8 +18,12 @@ class App < Roda
     end
 
     r.get String do | url_code |
-      link = links.filter(:code => url_code).first[:url]
+      link = links.filter(:code => url_code)
-      r.redirect link
+      if link.first.nil?
+        flash['message'] = "Link #{url_code} doesn't exist"
+        r.redirect '/'
+      end
+      r.redirect link.first[:url]
     end
 
     r.post "create" do