fix: type of RouteDefinition

src/route.d.ts

@@ -37,9 +37,9 @@ export type RoutePostHandler<T = unknown, U = unknown> = (
 export type RouteDefinition = {
   method: string;
   path: string;
-  preHandler: RoutePreHandler | RoutePreHandler[];
+  preHandler: RoutePreHandler | RoutePreHandler[] | undefined;
   handler: RouteHandler;
-  postHandler: RoutePostHandler | RoutePostHandler[];
+  postHandler: RoutePostHandler | RoutePostHandler[] | undefined;
 };
 
 /**

src/route.js

@@ -12,9 +12,9 @@ import {getRequestPathname} from './utils/index.js';
  * @typedef {{
  *   method: string,
  *   path: string,
- *   preHandler: RoutePreHandler|(RoutePreHandler[])
+ *   preHandler: RoutePreHandler|(RoutePreHandler[])|undefined
  *   handler: RouteHandler,
- *   postHandler: RoutePostHandler|(RoutePostHandler[])
+ *   postHandler: RoutePostHandler|(RoutePostHandler[])|undefined
  * }} RouteDefinition
  */