OptionalendOptionalerrorLeave unset to model an undiagnosed driver failure (no errorInfo at all).
OptionalerrorOptionalexceptionOptionalomitWhen true, data is left unassigned (some driver failure paths return no
data at all). Default builds the empty { choices: [], usage } data that
BaseLLM's own error paths produce.
OptionalstartOptionalstatus
Options for makeFailedChatResult.