test: check for existence of debug flag before converging

molecule/resources/playbooks/converge.yml

@@ -16,6 +16,8 @@
     - name: print facts
       ansible.builtin.debug:
         var: ansible_facts
-      when: debug
+      when:
+        - debug is defined
+        - debug is true
   roles:
     - {role: "ansible_lza_install_common", become: true}