ErrorResponse
Structured error envelope. error is a stable machine-readable code, message a short category, and details a human-readable string naming what went wrong. Branch on error in client code.
- errorType: stringrequired
Stable machine-readable error code.
- messageType: stringrequired
Short human-readable category.
- detailsType: string
What went wrong, as a string (never a list or object).

