export declare function extractErrorCode(err: unknown): string | undefined;
export declare function readErrorName(err: unknown): string;
export declare function collectErrorGraphCandidates(err: unknown, resolveNested?: (current: Record<string, unknown>) => Iterable<unknown>): unknown[];
/**
 * Type guard for NodeJS.ErrnoException (any error with a `code` property).
 */
export declare function isErrno(err: unknown): err is NodeJS.ErrnoException;
/**
 * Check if an error has a specific errno code.
 */
export declare function hasErrnoCode(err: unknown, code: string): boolean;
export declare function formatErrorMessage(err: unknown): string;
export declare function formatUncaughtError(err: unknown): string;