FIX: when uploads are destroyed clear up avatar refs in user table

This also auto corrects twice daily when we ensure consistency

app/models/user.rb

@@ -1283,6 +1283,20 @@ class User < ActiveRecord::Base
     true
   end
 
+  def self.ensure_consistency!
+    DB.exec <<~SQL
+      UPDATE users
+      SET uploaded_avatar_id = NULL
+      WHERE uploaded_avatar_id IN (
+        SELECT u1.uploaded_avatar_id FROM users u1
+        LEFT JOIN uploads up
+          ON u1.uploaded_avatar_id = up.id
+        WHERE u1.uploaded_avatar_id IS NOT NULL AND
+          up.id IS NULL
+      )
+    SQL
+  end
+
 end
 
 # == Schema Information