Improve error handling for IdempotentParamaterMismatch (#30324)

Ensure all the return variables are correctly populated
and return more info in the error message

lib/ansible/modules/cloud/amazon/ec2_vpc_nat_gateway.py

@@ -707,13 +707,13 @@ def create(client, subnet_id, allocation_id, client_token=None,
     except botocore.exceptions.ClientError as e:
         if "IdempotentParameterMismatch" in e.message:
             err_msg = (
-                'NAT Gateway does not support update and token has already been provided'
+                'NAT Gateway does not support update and token has already been provided: ' + str(e)
             )
         else:
             err_msg = str(e)
-            success = False
-            changed = False
-            result = None
+        success = False
+        changed = False
+        result = None
 
     return success, changed, err_msg, result