search_data verify if collection owner is nil

app/models/collection.rb

@@ -74,11 +74,12 @@ class Collection < ApplicationRecord
   has_paper_trail
 
   def search_data
+    owner_name = (owner.nil? || owner.name.blank?) ? "" : owner.name
     {
       name: name,
       description: description,
       privacy: privacy,
-      owner: owner.name,
+      owner: owner_name,
       tags: tags.map(&:name),
       subjects: subjects.pluck(:id),
       educational_stages: educational_stages.pluck(:id),