Weird behavior in very simple App.js building.

[FateRiddle]

The published bundle somehow couldn't work and I don't know why, so I tried to make App.js really simple:

function App() {
  return 'hello';
}

export default App;

and run npm run build
the result will be an empty css file (even though I delete .css file in src) and an js file:

"use strict";

Which is definite a wrong output.

What's the hidden rule in this building process?

[hmaurer]

It will be difficult to identify the source of your problem without a reliable way to reproduce it. Could you share a complete minimal example? (including the version of Vite that you are using).