[Bug] next/font not working on Windows

[izakgl]

Describe the bug

The next/font mock does not work on windows.

Steps to reproduce the behavior

I created a reproduction repository with minimal setup (bootstraping nextjs, storybook and then adding fonts): https://github.com/izakgl/nextjs-storybook-vite

Steps:

1. Clone repo
2. Install dependencies
3. Run npm run storybook on a Windows machine
4. Open a button story

Expected behavior

Story shows up and fonts work as expected.

Screenshots and/or logs

The response for virtual inter is an empty object.

Environment

• OS: Windows
• Browser (if applicable): All browsers

Additional context

I pinpointed the issue to be here:

vite-plugin-storybook-nextjs/src/plugins/next-font/plugin.ts

Line 70 in d4f5a30

const pathSep = path.sep;

Because it's taking separator from node:path package, which is \\ on Windows, it then fails to detect the correct file as vite is loading this from next/font/google/target.css with forward slash separators. If I hardcode / there, then this also works on Windows.