Fix: 500 error returned if destroy request without HTTP referer

CHANGELOG

@@ -12,6 +12,7 @@ v 8.2.0 (unreleased)
   - Fix: Inability to reply to code comments in the MR view, if the MR comes from a fork
   - Use git follow flag for commits page when retrieve history for file or directory
   - Show merge request CI status on merge requests index page
+  - Fix: 500 error returned if destroy request without HTTP referer (Kazuki Shimizu)
 
 v 8.1.0
   - Ensure MySQL CI limits DB migrations occur after the fields have been created (Stan Hu)

app/controllers/projects_controller.rb

@@ -124,7 +124,7 @@ def destroy
     ::Projects::DestroyService.new(@project, current_user, {}).execute
     flash[:alert] = "Project '#{@project.name}' was deleted."
 
-    if request.referer.include?('/admin')
+    if request.referer.present? && request.referer.include?('/admin')
       redirect_to admin_namespaces_projects_path
     else
       redirect_to dashboard_projects_path