/**
 * Type guard to check if an unknown value is an Error object
 */
export declare function isError(error: unknown): error is Error;
/**
 * Type guard to check if an error is a Node.js system error
 */
export declare function isNodeError(error: unknown): error is NodeJS.ErrnoException;
/**
 * Safely extract an error message from an unknown error type
 */
export declare function getErrorMessage(error: unknown): string;
/**
 * Safely extract an error code from a Node.js error
 */
export declare function getErrorCode(error: unknown): string | undefined;
/**
 * Convert an unknown error to a proper Error object
 */
export declare function toError(error: unknown): Error;
/**
 * Create a formatted error message with optional context
 */
export declare function formatError(error: unknown, context?: string): string;