fix condition with non-boolean result

tasks/main.yml

@@ -19,7 +19,7 @@
            "user" if systemd_unit_scope == "global" else systemd_unit_scope
          ) }}
   register: _config_file
-  when: systemd_unit_config
+  when: systemd_unit_config is not none
 - name: 'create parent folder for drop-in config files of systemd unit {{ systemd_unit_name }}'
   file:
     path: '{{ _config_dir_path }}/{{ systemd_unit_name }}.d'