Enum ChainError 

#[non_exhaustive]
pub enum ChainError {
    MissingInput(String),
    InputError(String),
    OutputError(String),
    ExecutionError(String),
    StreamError(String),
    Other(String),
    Nested {
        context: String,
        source: Box<dyn Error + Send + Sync>,
    },
}

Chain error type.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

MissingInput(String)

Missing input.

InputError(String)

Input error (present but malformed — e.g. a document that fails to deserialize).

OutputError(String)

Output error.

ExecutionError(String)

Execution error.

StreamError(String)

Stream error.

Other(String)

Other error.

Nested

Nested (sub-chain / LLM) execution error, preserving the original error chain.

P2-1: composite chains (SequentialChain / RouterChain) wrap sub-chain or LLM failures in this variant so the underlying error stays inspectable via source() (e.g. downcast back to a concrete ChainError variant) instead of being flattened into a string by format!.

Fields

context: String

Human-readable context describing which step/chain failed.

source: Box<dyn Error + Send + Sync>

The underlying error, preserved for chaining.

Trait Implementations

impl Debug for ChainError

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ChainError

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for ChainError

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<ChainError> for LcelError

Allow ChainError to convert into LcelError.

fn from(err: ChainError) -> Self

Converts to this type from the input type.