Constant embedded_error_chain::ERROR_CHAIN_LEN

pub const ERROR_CHAIN_LEN: usize = 4;

The maximum amount of error codes that can be chained to an Error.

This is equal to the amount of ErrorData::chain() (or ChainError::chain(), ResultChainError::chain_err()) you can make before the chain overflows, and it either panics (if the feature panic-on-overflow is enabled) or the oldest error code gets lost.