pub const ERROR_OF: FreeBuiltinSchema;Expand description
Error(message: String) -> Error, the one constructor whose payload has a
type of its own rather than one the call site settles.
Its one parameter is MESSAGE_FIELD, the field the value it builds
carries, so the label a call writes and the label a read writes cannot
come apart.
The constant is not called ERROR because BuiltinType::Error’s type
table already is.