Handle case when OpenAI is too busy #3

Unexpected chunk: {
  "error": {
    "message": "That model is currently overloaded with other requests. You can retry your request, or contact us through our help center at help.openai.com if the error persists. (Please include the request ID b7676fdd3120b2dbb5048bc05da29701 in your message.)",
    "type": "server_error",
    "param": null,
    "code": null
  }
}