Fix prechecks

Author: mnasiadka

roles/vault_pki/tasks/prechecks.yml

@@ -1,12 +1,12 @@
 ---
 - name: "Fail if variables are not set"
   fail:
-    msg: "variable {{ item }} is not set"
+    msg: "variable {{ item.name }} is not set"
   when:
     - vars[item.name] | length == 0
     - item.when
   loop:
     - { "name": "vault_api_addr", "when": true }
     - { "name": "vault_token", when: true }
-    - { "name": "vault_pki_root_ca_name", "when": "vault_pki_root_create | bool" }
-    - { "name": "vault_pki_intermediate_ca_name", "when": "vault_pki_intermediate_create | bool" }
+    - { "name": "vault_pki_root_ca_name", "when": "{{ vault_pki_root_create | bool }}" }
+    - { "name": "vault_pki_intermediate_ca_name", "when": "{{ vault_pki_intermediate_create | bool }}" }