import { UpgradeHeaders } from "./http/UpgradeRequest";
export type Writable<T> = {
    -readonly [P in keyof T]: T[P];
};
export declare function tryGetClientIpFromHeaders(headers: UpgradeHeaders): string | undefined;
export declare function preprocessPath(path: string): string;
/**
 * Ensures that any catched value is an instance of Error.
 * @param err
 * @returns
 */
export declare function ensureError(err: any): Error;