[fix] improve type of init (#2544)

Author: benmccann

.changeset/five-bags-prove.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[fix] improve type of `init`

packages/kit/src/core/preview/index.js

@@ -35,7 +35,7 @@ export async function preview({
 
 	const app_file = resolve(cwd, `${SVELTE_KIT}/output/server/app.js`);
 
-	/** @type {import('types/app').App} */
+	/** @type {import('types/internal').App} */
 	const app = await import(pathToFileURL(app_file).href);
 
 	/** @type {import('sirv').RequestHandler} */

packages/kit/types/app.d.ts

@@ -2,14 +2,7 @@ import { ReadOnlyFormData, RequestHeaders } from './helper';
 import { ServerResponse } from './hooks';
 
 export interface App {
-	init(options?: {
-		paths: {
-			base: string;
-			assets: string;
-		};
-		prerendering: boolean;
-		read(file: string): Buffer;
-	}): void;
+	init(): void;
 	render(incoming: IncomingRequest): Promise<ServerResponse>;
 }
 

packages/kit/types/internal.d.ts

@@ -19,6 +19,15 @@ export interface PrerenderOptions {
 }
 
 export interface App extends PublicApp {
+	init(options?: {
+		paths: {
+			base: string;
+			assets: string;
+		};
+		prerendering: boolean;
+		read(file: string): Buffer;
+	}): void;
+
 	render(
 		incoming: IncomingRequest,
 		options?: {