Merge pull request #2233 from ZeiP/bug/1929_broken_feed_missing_tag

#1929: Fix the actions query breaking when querying actions with a no…

app/models/todos/undone_todos_query.rb

@@ -27,6 +27,7 @@ module Todos
 
       if params[:tag]
         tag = Tag.where(:name => params[:tag]).first
+        return [] if !tag
         not_done_todos = not_done_todos.joins(:taggings).where('taggings.tag_id = ?', tag.id)
       end
 

test/integration/feed_smoke_test.rb

@@ -84,6 +84,10 @@ class FeedSmokeTest < ActionDispatch::IntegrationTest
     assert_success "/todos.rss?token=#{ users(:admin_user).token }&done=7"
   end
   
+  def test_all_starred_active_actions_rss
+    assert_success "/todos.rss?token=#{ users(:admin_user).token }&tag=starred"
+  end
+
   def test_all_actions_completed_in_last_7_days_txt
     assert_success "/todos.txt?token=#{ users(:admin_user).token }&done=7"
   end