/**
 * Custom error class for RELAY protocol errors.
 *
 * Thrown when the server returns a non-2xx JSON-RPC result code. Mirrors the
 * Python SDK signature: `RelayError(code, message)`.
 */
export declare class RelayError extends Error {
    /** Numeric RELAY result code returned by the server. */
    readonly code: number;
    /**
     * @param code - Numeric RELAY result code (e.g. `404`, `503`).
     * @param message - Human-readable error message from the server.
     */
    constructor(code: number, message: string);
}