fix(create-vite): ts error in the svelte-ts template (#16031)

Author: twharmon

packages/create-vite/template-svelte-ts/src/main.ts

@@ -2,7 +2,7 @@ import './app.css'
 import App from './App.svelte'
 
 const app = new App({
-  target: document.getElementById('app'),
+  target: document.getElementById('app')!,
 })
 
 export default app