DELETE <pub>/relations API returns 400 when it should return 200

[gabestein]

What went wrong, step-by-step?

1. Delete a relation from a pub using the API
2. It will return a 400 with the error: Error: No fields found for slugs:
3. But it will have successfully deleted the relation

e.g.:

DELETE https://app.pubpub.org/api/v0/c/arcadia-dev/site/pubs/c7e02fdc-e3bf-4422-a5f7-8e112e3b3e8d/relations
Authorization: Bearer <token>
Prefer: "return=representation"
Accept: "*/*"
Content-Type: "application/json",

{
  "arcadia-dev:pub-content-types": [ "0a8b81c9-e025-4e08-94aa-f669630b62f0" ]
}

What did you expect to happen?

Returns a 200

What URL can we use to see the issue?

What browser/operating system were you using?

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Who reported this? (If not you)