_error.page.js

The page _error.page.js is rendered when:

1. None of our pages matches the URL (404 Page Not Found).
2. One of our hooks (in .page.js / .page.server.js / .page.route.js) throws an error (500 Internal Server Error).
3. One of our hooks executes throw RenderErrorPage().

For 1. and 3., vite-plugin-ssr automatically sets the following:

• pageContext.is404 === true
• pageContext.pageProps.is404 === true

We can throw RenderErrorPage({ pageContext: { is404: false }}) to have pageContext.is404 === false as well as pageContext.pageProps.is404 === false.

For 2.:

• pageContext.is404 === false
• pageContext.pageProps.is404 === false

Normally, the vite-plugin-ssr source code doesn't know anything about pageContext.pageProps but this is the only exception.

That way, we can use pageContext.pageProps.is404 to decide what error message to show our user:

// _error.page.js

export { Page }

function Page(pageProps) {
  if (pageProps.is404) {
    // UI component showing the user a message like "Page Not Found"
  } else {
    // UI component showing the user a message like "Our server is down, sincere apologies."
  }
}

We can define _error.page.js like any other page, for example with _error.page.client.js and _error.page.server.js.