Is it possible to upload an image to custom API?

I am getting an error when posting to a custom API endpoint. I am using multipart/form-data but I just get a 500 internal server error. The preview of the file is [object File] which makes me look like WeWeb doesn’t support this yet?

There is no value getting picked up for document, here is WeWebs request

{
  "url": "http://bnkability-staging-001.eu-west-2.elasticbeanstalk.com/api/v1/document",
  "method": "POST",
  "data": [
    {
      "key": "document",
      "value": {}
    },
    {
      "key": "title",
      "value": "Memorandum and articles of association"
    }
  ],
  "headers": [
    {
      "key": "Authorization",
      "value": "Bearer XXXXXX"
    }
  ]
}