fix: missing export of imported Invalidator type

fixes https://github.com/sveltejs/svelte/issues/12276

Signed-off-by: Florent Benoit <fbenoit@redhat.com>

packages/svelte/src/store/public.d.ts

@@ -48,6 +48,6 @@ interface Writable<T> extends Readable<T> {
 	update(this: void, updater: Updater<T>): void;
 }
 
-export { Readable, StartStopNotifier, Subscriber, Unsubscriber, Updater, Writable };
+export { Invalidator, Readable, StartStopNotifier, Subscriber, Unsubscriber, Updater, Writable };
 
 export * from './index.js';

packages/svelte/tests/store/test.ts

@@ -1,5 +1,13 @@
 import { describe, it, assert } from 'vitest';
-import { readable, writable, derived, get, readonly, type Readable } from 'svelte/store';
+import {
+	readable,
+	writable,
+	derived,
+	get,
+	readonly,
+	type Readable,
+	type Invalidator
+} from 'svelte/store';
 
 describe('writable', () => {
 	it('creates a writable store', () => {
@@ -574,3 +582,13 @@ describe('readonly', () => {
 		assert.throws(() => readableStore.set(3));
 	});
 });
+
+describe('type Invalidator', () => {
+	it('check it is exported from the store', () => {
+		// dummy test importing Invalidator from store
+		// to check if it is exported
+		// it will fail with tsc if not exported
+		const invalidator: Invalidator<number> = () => {};
+		assert.equal(typeof invalidator, 'function');
+	});
+});

packages/svelte/types/index.d.ts

@@ -2298,7 +2298,7 @@ declare module 'svelte/store' {
 	 * */
 	export function get<T>(store: Readable<T>): T;
 
-	export { Subscriber, Unsubscriber, Updater, StartStopNotifier, Readable, Writable };
+	export { Subscriber, Unsubscriber, Updater, StartStopNotifier, Readable, Writable, Invalidator };
 }
 
 declare module 'svelte/transition' {