Add info on rendering an error page when using getServerSideProps (#3…

…4488)

This PR adds information on rendering an error page (500 page specifically) when using `getServerSideProps`.

## Bug

- [x] Related issues linked using https://github.com/vercel/documentation/issues/106
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `yarn lint`


Co-authored-by: JJ Kasper <22380829+ijjk@users.noreply.github.com>

docs/basic-features/data-fetching/get-server-side-props.md

@@ -47,8 +47,8 @@ Take the following example. An API route is used to fetch some data from a CMS.
 
 If your page contains frequently updating data, and you don’t need to pre-render the data, you can fetch the data on the [client side](/docs/basic-features/data-fetching/client-side.md). An example of this is user-specific data:
 
-- First, immediately show the page without data. Parts of the page can be pre-rendered using Static Generation. You can show loading states for missing data.
-- Then, fetch the data on the client side and display it when ready.
+- First, immediately show the page without data. Parts of the page can be pre-rendered using Static Generation. You can show loading states for missing data
+- Then, fetch the data on the client side and display it when ready
 
 This approach works well for user dashboard pages, for example. Because a dashboard is a private, user-specific page, SEO is not relevant and the page doesn’t need to be pre-rendered. The data is frequently updated, which requires request-time data fetching.
 
@@ -74,6 +74,10 @@ export async function getServerSideProps() {
 export default Page
 ```
 
+## Does getServerSideProps render an error page
+
+If an error is thrown inside `getServerSideProps`, it will show the `pages/500.js` file. Check out the documentation for [500 page](/docs/advanced-features/custom-error-page#500-page) to learn more on how to create it. During development this file will not be used and the dev overlay will be shown instead.
+
 ## Related
 
 For more information on what to do next, we recommend the following sections: