fix: amend onNavigate type (#11599)

closes #11564

.changeset/tall-dots-agree.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+fix: amend onNavigate type

packages/kit/src/runtime/client/client.js

@@ -1608,7 +1608,7 @@ export function beforeNavigate(callback) {
  * If a function (or a `Promise` that resolves to a function) is returned from the callback, it will be called once the DOM has updated.
  *
  * `onNavigate` must be called during a component initialization. It remains active as long as the component is mounted.
- * @param {(navigation: import('@sveltejs/kit').OnNavigate) => import('types').MaybePromise<void>} callback
+ * @param {(navigation: import('@sveltejs/kit').OnNavigate) => import('types').MaybePromise<(() => void) | void>} callback
  * @returns {void}
  */
 export function onNavigate(callback) {

packages/kit/types/index.d.ts

@@ -1981,7 +1981,7 @@ declare module '$app/navigation' {
 	 *
 	 * `onNavigate` must be called during a component initialization. It remains active as long as the component is mounted.
 	 * */
-	export function onNavigate(callback: (navigation: import('@sveltejs/kit').OnNavigate) => MaybePromise<void>): void;
+	export function onNavigate(callback: (navigation: import('@sveltejs/kit').OnNavigate) => MaybePromise<(() => void) | void>): void;
 	/**
 	 * If called when the page is being updated following a navigation (in `onMount` or `afterNavigate` or an action, for example), this disables SvelteKit's built-in scroll handling.
 	 * This is generally discouraged, since it breaks user expectations.