Include defaults in condition such that it won't fail

tasks/install.yml

@@ -224,5 +224,5 @@
 - name: "Run Post Deploy Tasks"
   shell: drush -y @{{ inventory_hostname }}{{ drushSubkey }} {{ item }}
   with_items: '{{ drupal_post_deploy_tasks[drupal.version|default("d7")] }}'
-  when: "drush_status is defined and ('Successful' in drush_status.stdout or 'Erfolgreich' in drush_status.stdout)"
+  when: "drush_status is defined and ('Successful' in drush_status.stdout|default('') or 'Erfolgreich' in drush_status.stdout|default(''))"
   tags: 'deploy'