Roles only run on intended supported OS, and minor cleanup of when statements to match

roles/ensure_hostname/tasks/main.yml

@@ -1,8 +1,22 @@
 ---
 # tasks file for ensure_hostname
+- name: Assert Target OS Is Supported
+  when:
+    - ansible_facts["system"] is defined
+  ansible.builtin.assert:
+    fail_msg: "Unsupported OS: {{ ansible_facts['system'] | default('unknown') }}"
+    quiet: true
+    that:
+      - ansible_facts["system"] == 'Linux'
 - name: Set Hostname If Localhost
   when:
-    - ansible_facts["system"] == 'Linux'
     - ansible_facts["fqdn"] == 'localhost.localdomain'
   ansible.builtin.hostname:
     name: '{{ inventory_hostname }}'
+- name: Assert Hostname Verification
+  ansible.builtin.assert:
+    fail_msg: "Hostname is not defined"
+    quiet: true
+    that:
+      - ansible_facts["nodename"] is defined
+      - ansible_facts["nodename"] != ''