Use non-null assertion instead of type assertion in createRoot()

Author: wojtekmaj

sample/index.tsx

@@ -3,4 +3,4 @@ import { createRoot } from 'react-dom/client';
 
 import Sample from './Sample.js';
 
-createRoot(document.getElementById('react-root') as HTMLDivElement).render(<Sample />);
+createRoot(document.getElementById('react-root')!).render(<Sample />);

test/index.tsx

@@ -3,7 +3,7 @@ import { createRoot } from 'react-dom/client';
 
 import Test from './Test.js';
 
-createRoot(document.getElementById('react-root') as HTMLDivElement).render(
+createRoot(document.getElementById('react-root')!).render(
   <StrictMode>
     <Test />
   </StrictMode>,