app/models/spotlight/lock.rb in blacklight-spotlight-0.34.1 vs app/models/spotlight/lock.rb in blacklight-spotlight-1.0.0.alpha1

@@ -1,10 +1,10 @@
 module Spotlight
   ##
   # Page-level locking to discourage update conflicts
   class Lock < ActiveRecord::Base
     belongs_to :on, polymorphic: true
-    belongs_to :by, polymorphic: true
+    belongs_to :by, polymorphic: true, optional: true
 
     def current_session!
       @current_session = true
     end