Add 'Vote not found'

vedia.rb

@@ -319,17 +319,21 @@ end
 get '/votes/:id' do
   require_login
   find_vote
-  case @vote.state
-  when 'draft'
-    if @vote.users.exists?(current_user.id)
-      erb :votes_edit
-    else
-      erb :votes_show_draft
+  if not @vote
+    erb :votes_show_unknown
+  else
+    case @vote.state
+    when 'draft'
+      if @vote.users.exists?(current_user.id)
+        erb :votes_edit
+      else
+        erb :votes_show_draft
+      end
+    when 'open'
+      erb :votes_show_open
+    when 'closed'
+      erb :votes_show_closed
     end
-  when 'open'
-    erb :votes_show_open
-  when 'closed'
-    erb :votes_show_closed
   end
 end