Fix TypeScript errors in examples

Author: Rel1cx

examples/react-dom/src/main.ts

@@ -4,4 +4,4 @@ import ReactDOM from "react-dom/client";
 
 import { root } from "./root";
 
-ReactDOM.createRoot(document.querySelector("#root")).render(root);
+ReactDOM.createRoot(document.querySelector("#root")!).render(root);