Error handling with different error structures in my custom Integromat app

I have an API that returns different error structures for different endpoints and status codes. Sometimes it's a string, sometimes a complex object or an array. Since Integromat requires all error handling to be done in one place in the Base and not in the modules, how can I implement this correctly? Case 1

  "data": {
    "error": {
      "user_ids.0": [
        "The user_ids.0 must be an integer."
      ]
    }
  }

Case 2

  "data": {
    "error": "Not found"
  }

It is possible to use the JavaScript function for processing the response and getting an error message. Please take a look at the example below:

Base:

{
"response": {
        "output": "...",
        "error": "{{parseErrorMessage(body)}}"
    }
}

function parseErrorMessage(body) {
  if ('string' === typeof body.data) return body.data;

  ...
}

Custom JS is disabled by default, please get in touch with our support to enable it. Ref: https://docs.integromat.com/apps/app-structure/iml-functions