Module errors 

Typed error enums for parametrisation, conversion, and calibration.

All failure paths return a typed Result — no panic!(), no unwrap(), no string errors. Each variant carries enough context for the caller to decide how to recover.

Three enums separate the three failure domains:

• ParamError — invalid SVI / SSVI parameters or out-of-domain quotes.
• ConvertError — a parametrisation conversion has no valid pre-image.
• CalibrationError — a calibrator could not produce a usable fit.

Enums

CalibrationError

Error returned when a calibrator cannot produce a usable fit.

ConvertError

Error returned when a parametrisation conversion has no valid pre-image.

ParamError

Error returned when SVI / SSVI parameters or market quotes fail validation.