Fix: new NotFound exception should be named NotFoundError

Author: Alexander Golovanov

src/index.js

@@ -1,4 +1,4 @@
 export { HTTPError } from "./http";
 export { AccessDeniedError } from "./access-denied";
 export { BadRequestError } from "./bad-request";
-export { NotFound } from "./not-found";
+export { NotFoundError } from "./not-found";

src/not-found.js

@@ -2,7 +2,7 @@
 
 import { HTTPError } from "./http";
 
-export class NotFound extends HTTPError {
+export class NotFoundError extends HTTPError {
     constructor( message, extra ) {
         super( 404, message || "Not Found", extra );
     }