Default Theme renders home page and 404 page unexpectedly

[nozomuikuta]

Describe the bug

I found default theme renders home page and 404 page unexpectedly, whose ways in which it happens differs from environment to another.

Reproduction

Case 1: the current website

Case 1-1 (expected):

• Access https://vitepress.vuejs.org/
• Change the URL to https://vitepress.vuejs.org/this-page-doesnt-exist
• 404 page is rendered as expected

Case 1-2 (unexpected):

• Access https://vitepress.vuejs.org/guide/getting-started.html (or, any pages that has sidebar)
• Change the URL to https://vitepress.vuejs.org/guide/this-page-doesnt-exist
• 404 page is rendered in 2 places unexpectedly
• Click a link in sidebar to change the URL
• One of 404 pages is still there while the other is replaced by the content of the page that you chose

---

Case 2: local development

Case 2-1 (expected):

• Run pnpm run docs in your local
• Access http://localhost:3000/
• Change the URL to http://localhost:3000/this-page-doesnt-exist
• 404 page is rendered as expected (cf. Case 1-1)

Case 2-2 (unexpected):

• Run pnpm run docs-build in your local
• Run pnpm run docs-serve in your local
• Access http://localhost:5000/
• Change the URL to http://localhost:5000/this-page-doesnt-exist
• 404 page is broken (it seems that div.VPHome is rendered instead of div.NotFound)

Case 2-3 (unexpected):

• Run pnpm run docs-build in your local
• Run pnpm run docs-serve in your local
• Access http://localhost:5000/
• Access http://localhost:5000/guide/getting-started.html (or, any pages that has sidebar)
• Change the URL to http://localhost:5000/guide/this-page-doesnt-exist
• Home page and 404 page is rendered unexpectedly (cf. Case 1-2)
• Click a link in sidebar to change the URL
• Home page is still there while 404 page is replaced by the content of the page that you chose

Expected behavior

Home page and 404 page are rendered only when they are supposed to be so.

System Info

Environment 1: https://vitepress.vuejs.org/ as of Jul 11th 2022
Environment 2: my local with the head of upstream's `main` branch checked out
---
  System:
    OS: macOS 12.3.1
    CPU: (8) arm64 Apple M1
    Memory: 1.15 GB / 16.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 16.15.1 - ~/.nvm/versions/node/v16.15.1/bin/node
    npm: 8.11.0 - ~/.nvm/versions/node/v16.15.1/bin/npm
  Browsers:
    Chrome: 103.0.5060.114
    Safari: 15.4
---

Additional context

I'm not so familiar with VitePress' implementation, so I don't have an idea at the moment.
I will post comments when I find something related.

Validations

• Follow our Code of Conduct
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.

[brc-dd]

Hi! Can you checkout fix/404 branch and see if the issues are resolved.

[nozomuikuta]

Hi, sorry for late reply.
I confirmed that Case 1-2, Case 2-2, and Case 2-3 are all fixed in the website and at the latest commit of main branch. 👍