chore: clean up emulator types (#11737)

* chore: clean up emulator types

- the Emulator type is not a class export
- make validated config types more correct by leaving adapter types as optional

* fix

* ok that doesnt work for some reason

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>

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

@@ -19,7 +19,8 @@ export async function adapt(
 	log,
 	vite_config
 ) {
-	const { name, adapt } = config.kit.adapter;
+	// This is only called when adapter is truthy, so the cast is safe
+	const { name, adapt } = /** @type {import('@sveltejs/kit').Adapter} */ (config.kit.adapter);
 
 	console.log(colors.bold().cyan(`\n> Using ${name}`));
 

packages/kit/src/exports/public.d.ts

@@ -268,7 +268,7 @@ export interface Cookies {
 /**
  * A collection of functions that influence the environment during dev, build and prerendering
  */
-export class Emulator {
+export interface Emulator {
 	/**
 	 * A function that is called with the current route `config` and `prerender` option
 	 * and returns an `App.Platform` object

packages/kit/src/exports/vite/dev/index.js

@@ -419,8 +419,6 @@ export async function dev(vite, vite_config, svelte_config) {
 	});
 
 	const env = loadEnv(vite_config.mode, svelte_config.kit.env.dir, '');
-
-	// TODO because of `RecursiveRequired`, TypeScript thinks this is guaranteed to exist, but it isn't
 	const emulator = await svelte_config.kit.adapter?.emulate?.();
 
 	return () => {

packages/kit/src/exports/vite/index.js

@@ -164,7 +164,6 @@ export async function sveltekit() {
 		preprocess,
 		onwarn: svelte_config.onwarn,
 		compilerOptions: {
-			// @ts-expect-error SvelteKit requires hydratable true by default
 			hydratable: isSvelte5Plus() ? undefined : true,
 			...svelte_config.compilerOptions
 		},

packages/kit/src/exports/vite/preview/index.js

@@ -51,7 +51,6 @@ export async function preview(vite, vite_config, svelte_config) {
 		read: (file) => createReadableStream(`${dir}/${file}`)
 	});
 
-	// TODO because of `RecursiveRequired`, TypeScript thinks this is guaranteed to exist, but it isn't
 	const emulator = await svelte_config.kit.adapter?.emulate?.();
 
 	return () => {

packages/kit/src/types/internal.d.ts

@@ -16,7 +16,8 @@ import {
 	Reroute,
 	RequestEvent,
 	SSRManifest,
-	Emulator
+	Emulator,
+	Adapter
 } from '@sveltejs/kit';
 import {
 	HttpMethod,
@@ -434,9 +435,14 @@ export interface Uses {
 	search_params: Set<string>;
 }
 
-export type ValidatedConfig = RecursiveRequired<Config>;
+export type ValidatedConfig = Config & {
+	kit: ValidatedKitConfig;
+	extensions: string[];
+};
 
-export type ValidatedKitConfig = RecursiveRequired<KitConfig>;
+export type ValidatedKitConfig = Omit<RecursiveRequired<KitConfig>, 'adapter'> & {
+	adapter?: Adapter;
+};
 
 export * from '../exports/index.js';
 export * from './private.js';

packages/kit/types/index.d.ts

@@ -250,7 +250,7 @@ declare module '@sveltejs/kit' {
 	/**
 	 * A collection of functions that influence the environment during dev, build and prerendering
 	 */
-	export class Emulator {
+	export interface Emulator {
 		/**
 		 * A function that is called with the current route `config` and `prerender` option
 		 * and returns an `App.Platform` object
@@ -1748,7 +1748,14 @@ declare module '@sveltejs/kit' {
 		endpoint_id?: string;
 	}
 
-	type ValidatedConfig = RecursiveRequired<Config>;
+	type ValidatedConfig = Config & {
+		kit: ValidatedKitConfig;
+		extensions: string[];
+	};
+
+	type ValidatedKitConfig = Omit<RecursiveRequired<KitConfig>, 'adapter'> & {
+		adapter?: Adapter;
+	};
 	/**
 	 * Throws an error with a HTTP status code and an optional message.
 	 * When called during request handling, this will cause SvelteKit to