Error events - Nito

Mid-Stream

If generation fails after the stream has begun, a chunk carries a top-level error and a terminal choice:

{
  "id": "...",
  "object": "chat.completion.chunk",
  "created": 1751299200,
  "model": "z-ai/glm-5.2",
  "error": { "message": "human-readable description", "code": "provider_error", "param": null },
  "choices": [
    { "index": 0, "delta": {}, "finish_reason": "error" }
  ]
}

Field	Notes
`error.message`	Human-readable description.
`error.code`	The error family. Same families as the error format.
`error.param`	Optional. The field the error refers to, when applicable.
`choices[0].finish_reason`	`error`. See Finish reasons.

Content streamed before this chunk is partial. The stream still ends with [DONE].

Before the First Byte

A request rejected before any byte is written (auth, validation, limits, a provider that never opened) returns a normal HTTP error with the standard envelope. See Error format. A streaming client therefore handles two shapes: a non-200 response with a JSON body, and a 200 stream that later carries an error chunk.