correct entry point to use onInit method

src/Umbraco.Web.UI.Client/public-assets/App_Plugins/custom-entrypoint.js

@@ -1,4 +1,4 @@
 console.log('Hello from the custom entrypoint file!');
-export default function () {
-	console.log('Hello from the custom entrypoint inside the default function!');
+export function onInit() {
+	console.log('Hello from the custom entrypoint inside the onInit function!');
 }