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]
-      r.redirect link
+      link = links.filter(:code => url_code)
+      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

features/homepage.feature

@@ -42,5 +42,5 @@ Feature: Homepage
 
   Scenario: Accessing a nonexistent URL code
     Given I visit the "/aaaaaa" location
-    Then I should be redirected to "/"
+    Then I should be on "/" page
     And I should see the message "Link aaaaaa doesn't exist"