Graphic API error: Problem processing request

Question

This mutation fails:
```
mutation($input:VariableUpsertInput!) {
  variableUpsert(input:$input)
}

// variables:
{
  "input": {
    "environmentId": "***",
    "name":"***",
    "projectId": "***",
    "serviceId": "***",
    "value": "***"
  }
}
```
The error is:
```
{
  "errors": [
    {
      "message": "Problem processing request",
      "traceId": "3707103883129546512"
    }
  ],
  "data": null
}
```
I'm just trying to add a variable to a service. I'm (almost) certain my variables are correct.
I've done other similar mutations that works so its nothing wrong with my auth/syntax afaik.
Any help appreciated!

PS - I'd love to use the railway cli instead of graphql, as I'm making a github action, but afaik you need to do railway login which is not possible through github actions?

Thanks in advance!