How to set custom error in strong-error-handler when debug mode is false

Question

I'm using Loopback v3.x, and strong-error-handler for handling my project errors. The error response was fine in the development mode but when in production mode, it throws a different error back to the client.

I realised that it was the "debug": false" that makes it throw an { error: { statusCode: 500, message: 'Internal Server Error' } } (based from the Loopback documentation about strong-error-handler)

But I wanted to show my error in the production when I throw new Error('Error Messages') with "debug": false (to keep the sensitive data such as file paths, URLs, and stack traces out from exposure)

Below are my config files:

config.json

{
  ...
  "remoting": {
    "rest": {
      "normalizeHttpPath": false,
      "xml": false,
      "handleErrors": false
    }
  }
}

middleware.development.json

{
  "final:after": {
    "strong-error-handler": {
      "params": {
        "debug": true,
        "log": true,
        "safeFields": [
          "code"
        ]
      }
    }
  }
}

middleware.json

{
  "final:after": {
    "strong-error-handler": {
      "params": {
        "debug": false,
        "log": true,
        "safeFields": [
          "code"
        ]
      }
    }
  }
}

I wanted the response to show the Error that I have thrown, like below:

Instead, now it receives:

I have went to strongloop-error-handler GitHub library but couldn't find any documentation about throwing the original error. Is it possible to do so?

Answer 1

So I went digging around the strong-error-handler library and found out that it is technically possible to do so if we set a statusCode into the error manually, and has to be within 400 - 499.

in buildResponseData() function:

if (data.statusCode >= 400 && data.statusCode <= 499) {
  fillBadRequestError(data, err);
} else {
  fillInternalError(data, err);
}

https://github.com/strongloop/strong-error-handler/blob/master/lib/data-builder.js#L37

and the fillBadRequestError() will return the original error

function fillBadRequestError(data, err) {
  data.name = err.name;
  data.message = err.message;
  data.code = err.code;
  data.details = err.details;
}

https://github.com/strongloop/strong-error-handler/blob/master/lib/data-builder.js#L69

So, before throwing the error, we can set:

const error = new Error();
error.name = 'Custom Error';
error.message = 'Error Message';
error.statusCode = 404;
throw error;

Then it will return the error even with "debug": false mode