Change

app/views/users/projects/shared/_project.json.jbuilder

@@ -5,8 +5,8 @@ json.members_count project.members.count
 json.issues_count project.issues.count
 json.changesets_count project.project_score&.changeset_num.to_i
 
-json.is_public project.is_public?
-json.can_visited project.can_visited?
+json.is_public project&.is_public
+json.can_visited project&.can_visited?
 
 json.owner do
   json.partial! 'users/shared/real_user', user: project.owner

app/views/users/subjects/shared/_subject.json.jbuilder

@@ -5,4 +5,4 @@ json.image_url url_to_avatar(subject)
 json.owner_id subject.user.id
 json.owner_name subject.user.full_name
 json.visits_count subject.visits
-json.can_visited subject.can_visited?
+json.can_visited subject&.can_visited?