Adding a safe method operator in case the project is missing

app/serializers/base_discussion_entity.rb

@@ -40,7 +40,7 @@ class BaseDiscussionEntity < Grape::Entity
     end
 
     expose :resolve_with_issue_path do |discussion|
-      new_project_issue_path(discussion.project, merge_request_to_resolve_discussions_of: discussion.noteable.iid, discussion_to_resolve: discussion.id) if discussion.project.issues_enabled?
+      new_project_issue_path(discussion.project, merge_request_to_resolve_discussions_of: discussion.noteable.iid, discussion_to_resolve: discussion.id) if discussion&.project&.issues_enabled?
     end
   end