ErrorEnvelope

The shared /api2 failure envelope.

error_type and extra_data are artefacts of the shared handler: "" and [] on a 400, null on every other status. Neither carries information for these endpoints -- ignore both.

{
    "result": "failed",
    "code": 0,
    "message": "string",
    "error_type": "string",
    "extra_data": [
        null
    ]
}