fix value does not exist error

Author: crosmuller

roles/mongo/tasks/cluster.yml

@@ -41,11 +41,15 @@
 - name: Set fact for arbiter index number
   ansible.builtin.set_fact:
     arbiter_index: "{{ hostid }}"
-  when: hostvars[item].mongo_arbiter
+  when: hostvars[item].mongo_arbiter is defined and hostvars[item].mongo_arbiter
   loop: "{{ mongo_servers }}"
   loop_control:
     index_var: hostid
 
+- name: Debug host_id
+  ansible.builtin.debug:
+    msg: "{{ hostid }}"
+
 - name: Initial cluster initialisation
   community.mongodb.mongodb_replicaset:
     login_host: localhost