cloudstack: cs_instance: fix missing resource error in check mode if instance is not yet present

cloud/cloudstack/cs_instance.py

@@ -486,7 +486,9 @@ class AnsibleCloudStackInstance(AnsibleCloudStack):
         else:
             instance = self.update_instance(instance)
 
-        instance = self.ensure_tags(resource=instance, resource_type='UserVm')
+        # In check mode, we do not necessarely have an instance
+        if instance:
+            instance = self.ensure_tags(resource=instance, resource_type='UserVm')
 
         return instance