feat: return empty strings for outputs if module is disabled

Author: sgtoj

outputs.tf

@@ -1,9 +1,9 @@
 output "lambda_function_arn" {
   description = "The ARN of the EIP manager Lambda function"
-  value       = aws_lambda_function.this[0].arn
+  value       = module.this.enabled ? aws_lambda_function.this[0].arn : ""
 }
 
 output "iam_role_arn" {
   description = "The ARN of the IAM role used by the EIP manager Lambda function"
-  value       = aws_iam_role.this[0].arn
+  value       = module.this.enabled ? aws_iam_role.this[0].arn : ""
 }