Raised when the processor rejects an idempotency key replay (e.g., same key used for a different request body). Pattern-match on %Accrue.IdempotencyError{} to surface a user-facing "this request was already processed" message.
%Accrue.IdempotencyError{}
@type t() :: %Accrue.IdempotencyError{ __exception__: true, idempotency_key: term(), message: term(), processor_error: term() }