Bug: `TypeError: can't access property "self", data._jv.links is undefined` on `patchRelated`

[durk-cacholong]

🐛 Bug: TypeError: can't access property "self", data._jv.links is undefined on patchRelated

Description

A TypeError is thrown when performing a PATCH request on a relationship endpoint.
The error occurs even though the server response appears to be a valid JSON:API document.

This seems to happen because the response does not include links.self, and the client code attempts to access it unconditionally.

---

Error

TypeError: can't access property "self", data._jv.links is undefined
    writeRelated actions.js:75
    patchRelated actions.js:276
    wrappedAction pinia.mjs:1400
    actionName pinia.mjs:955

---

Endpoint

PATCH /some-resource/resource-4e4e-467a-8f7c-uuid/relationships/some-related-resource

---

Request Body

{
  "data": [
    {
      "type": "some-related-resource",
      "id": "some-85ca-43ed-8028-uuid"
    }
  ]
}

---

Response Body

{
  "jsonapi": {
    "version": "1.0"
  },
  "data": [
    {
      "type": "some-related-resource",
      "id": "some-85ca-43ed-8028-uuid"
    }
  ]
}

---

Expected Behavior

• The relationship update succeeds without throwing an error.
• The client should either:
  • Handle responses without links.self, or
  • Accept a 204 No Content response for relationship PATCH requests, which is valid per JSON:API.

---

Actual Behavior

• The request succeeds server-side, but the client throws:

  TypeError: can't access property "self", data._jv.links is undefined
  

• Execution fails in writeRelated / patchRelated.

---

Notes

• According to the JSON:API specification, a PATCH request to a relationship endpoint may return 204 No Content, and response bodies are optional.
• When a response body is returned, links are optional and should not be assumed to exist.

---

Possible Fix

• Add a null/undefined guard when accessing data._jv.links.self
• Or skip link processing for relationship PATCH responses