Fix the Lite custom element to initialize the app in the connected callback and dispose the app in the disconnected callback (#7577)

* Fix the Lite custom element to initialize the app in the connected callback and dispose the app in the disconnected callback

* add changeset

* Add type hints

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>

.changeset/cool-rocks-joke.md

@@ -0,0 +1,6 @@
+---
+"@gradio/app": minor
+"gradio": minor
+---
+
+feat:Fix the Lite custom element to initialize the app in the connected callback and dispose the app in the disconnected callback

js/app/src/lite/custom-element/index.ts

@@ -1,6 +1,10 @@
 // NOTE: We should only import the types from ".." to avoid the circular dependency of implementations,
 // which causes repeated executions of the ".." module in †he dev mode and can lead to multiple instances of the dev app.
-import type { create as createLiteAppFunc, Options } from "..";
+import type {
+	create as createLiteAppFunc,
+	Options,
+	GradioAppController
+} from "..";
 
 interface GradioComponentOptions {
 	info: Options["info"];
@@ -40,24 +44,33 @@ export function bootstrap_custom_element(
 	}
 
 	class GradioLiteAppElement extends HTMLElement {
-		constructor() {
-			super();
+		controller: GradioAppController | null = null;
 
-			const gradioComponentOptions = this.parseGradioComponentOptions();
-			const gradioLiteAppOptions = this.parseGradioLiteAppOptions();
+		connectedCallback(): void {
+			// At the time of connectedCallback, the child elements of the custom element are not yet parsed,
+			// so we need to defer the initialization to the next frame.
+			// Ref: https://stackoverflow.com/q/70949141/13103190
+			window.requestAnimationFrame(() => {
+				const gradioComponentOptions = this.parseGradioComponentOptions();
+				const gradioLiteAppOptions = this.parseGradioLiteAppOptions();
 
-			this.innerHTML = "";
+				this.innerHTML = "";
 
-			create({
-				target: this, // Same as `js/app/src/main.ts`
-				code: gradioLiteAppOptions.code,
-				requirements: gradioLiteAppOptions.requirements,
-				files: gradioLiteAppOptions.files,
-				entrypoint: gradioLiteAppOptions.entrypoint,
-				...gradioComponentOptions
+				this.controller = create({
+					target: this, // Same as `js/app/src/main.ts`
+					code: gradioLiteAppOptions.code,
+					requirements: gradioLiteAppOptions.requirements,
+					files: gradioLiteAppOptions.files,
+					entrypoint: gradioLiteAppOptions.entrypoint,
+					...gradioComponentOptions
+				});
 			});
 		}
 
+		disconnectedCallback(): void {
+			this.controller?.unmount();
+		}
+
 		parseGradioComponentOptions(): GradioComponentOptions {
 			// Parse the options from the attributes of the <gradio-lite> element.
 			// The following attributes are supported:

js/app/src/lite/index.ts

@@ -35,7 +35,7 @@ declare let GRADIO_VERSION: string;
 // As a result, the users of the Wasm app will have to load the CSS file manually.
 // const ENTRY_CSS = "__ENTRY_CSS__";
 
-interface GradioAppController {
+export interface GradioAppController {
 	run_code: (code: string) => Promise<void>;
 	run_file: (path: string) => Promise<void>;
 	write: (