Custom resolver not included in error responses

[MartinKolarik]

When a measurement is created with a custom resolver set but fails with an error, the resolver is not sent back in the response:

 "result": {
        "status": "failed",
        "statusCodeName": null,
        "statusCode": null,
        "rawOutput": "Private IP ranges are not allowed",
        "answers": [],
        "timings": {
          "total": 0
        },
        "resolver": null <- this should reflect the user's value
      }

Tested with DNS but may affect other types too.

[alexey-yarmosh]

In successful dns results resolver comes from the parsed result of a command, not from the user input. So if error happens before we parsed the response (https://github.com/jsdelivr/globalping-probe/blob/master/src/command/dns-command.ts#L132-L145) there is no resolver value to put to the result. We can use resolver from the user input in that case, but we will mix two sources in one field.

Another option is to set resolver when it was parsed and available (e.g. in case of "Private IP ranges are not allowed") and leave null value when it is not.

[MartinKolarik]

The case here was the target being private. In that case, it seems we have the info but don't use it?

[alexey-yarmosh]

Yes

[MartinKolarik]

Ok, so let's show it for cases where we have the value. It doesn't probably matter for real errors where we can't get it from the output, but here it does, because whether the target was private or may depend on the resolver used.