fix: removeChild may throw when render to document.body

[stormslowly]

Problem

// app.jsx
function Component() {
  // throw Error("toggle the error");
  return (
    <div>
      <div>Hello</div>
    </div>
  );
}  

// index.jsx
// render to body's directly
const root = ReactDOM.createRoot(document.getElementsByTagName("body")[0]);

Make the Component throw the error, then comment the throw again.
Overlay will appears as below.

• When user renders app to document.body and plugin shows some error
• User correct the error, then React re-renders document.body, removes the iframe which the plugin created and appened before; the plugin tries to remove it again. The error happens, and the overlay show a removeChild error.