[bug] exporting Default from a story with atleast one more export breaks sidebar active items

[jrson83]

Describe the bug

If you export const Default from a story where at least one other story is exported, the active item status in the sidebar is displayed incorrectly when you click on the Default story. The active CSS class is not only applied to the clicked link, but all items of the sidebar.

Reproduction

1. Clone the repo
2. Run pnpm i
3. Open buttons.stories.tsx in the docs package
4. On line 37 rename WithComponentProps to Default
5. Run pnpm dev
6. See the issue on the sidebar

Environment

• OS with version: Windows 11
• Browser with version: Firefox 117.0.1 & Chrome 119.0.6023.0 canary
• JS Runtime with version: NodeJS v20.2.0