Drupal calls should be avoided in classes, use dependency injection instead

The last submitted patch, 2: drupal_calls_should_be_avoided_3413764.patch, failed testing. View results →
- codesniffer_fixes.patch Interdiff of automated coding standards fixes only.

Thank you for reporting and proposing a fix. However, I think it is on purpose than basic auth service is not injected. The ShieldMiddleware does not depend on Basic Auth module to work. Before the service is used, the basic_auth module's status is checked.
The code you introduce does not check anything and will fail (missing/unknown service) on any site without basic_auth enabled.