change issue_tags_value error

app/views/pull_requests/edit.json.jbuilder

@@ -8,4 +8,4 @@ json.project_name @project.repository.try(:identifier)
 json.project_login  @project.owner.try(:login)
 json.extract! @pull_request, :id, :title, :body, :milestone,:head,:base,:is_original
 json.extract! @issue, :assigned_to_id, :fixed_version_id, :priority_id
-json.issue_tag_ids @issue.issue_tags_value.split(",")
+json.issue_tag_ids @issue&.issue_tags_value&.split(",")