Co-authored-by: NTim Neutkens <tim@timneutkens.nl>
Co-authored-by: Nkodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

This updates to not automatically export `/500` from `_error` if a custom `getInitialProps` is used since logic may be used inside of this method that causes the export to fail. Users can still opt-in to the static `/500` by adding a `pages/500.js` file. 

This also refactors checking `_app` for custom `getInitialProps` to outside of the static check loop to prevent a potential race condition where we could run this check multiple times un-necessarily.  

Fixes: https://github.com/vercel/next.js/issues/22815

This PR fixed a typo in api reference.

Hiya! I was asked to add an example of how to use [Compiled](https://compiledcssinjs.com/) with Next.js, figured I might as well at it to the source 😄. Let me know if there's any changes needed.

This ensures we load all env values before loading `next.config.js` since these values can be used in there. This also updates to ensure we're testing these values are available while loading `next.config.js` so we don't regress on this. 

Fixes: https://github.com/vercel/next.js/issues/22811

Upgrades webpack 5 to the latest version.

include scroll option documentation for router.push

Hi I saw you wrote extra async await code for command line function that doesn't need. I fixed that and code become very smaller and prettier.
![ts](https://user-images.githubusercontent.com/48912836/110254867-442c8880-7fa6-11eb-9f0f-3b853d5db94c.png)

Add note about restarting dev server on changes to tsconfig / jsconfig

This ensures we don't export `/404` during the automatic static optimization during build when the `/404` isn't static and won't be used/copied to the final output. 

x-ref: https://github.com/vercel/next.js/issues/22815

### Arabic/Hebrew RTL to `with-next-translate` Example
Added a simple example to change HTML direction based on the currently selected language

### References: 
- [#19049](https://github.com/vercel/next.js/discussions/19049)
- [#18667](https://github.com/vercel/next.js/issues/18667)

This PR adds request deduplication for `_getServerData`. If a request with the same URL is already in-flight, we don't send another new request. When a request succeeds or fails, we delete the cache.

A potential improvement this brings is, when `getServerSideProps` of a new route is slow to load, the user might keep clicking on the link which causes new requests, and the route will never update because results of old requests were ditched. Also adds a test case for this scenario.

Closes #19238.

In the current implementation, `idleTimeout` will always be thrown even if it didn't time out and `Promise.race` was resolved. This causes the error `Error: Route did not complete loading` on every route transition and Chrome Devtools will pause code execution if you have "Pause on exceptions" enabled.

This PR adds `resolvePromiseWithTimeout` which does the same thing as `Promise.race` and `idleTimeout`, but it cancels the rejection when it resolves successfully, in which case the error won't be thrown.

Fixes #21543.

This fixes the case where index page revalidation would match a dynamic page instead of the index page from the pathname not being denormalized. 

Fixes: https://github.com/vercel/next.js/issues/22750

Added preview example with Prepr CMS.

Working demo at https://next-blog-prepr.vercel.app/

Hey team!
We are updating the `with-supertokens` example to reflect the use of credentials alongside third party login

See: 
![image](https://user-images.githubusercontent.com/5072452/109943811-dd714b80-7cd5-11eb-91b5-5a966a1c1e2d.png)

This PR bumps the versions and add a base example implementation.

This updates the `NEXT_LOCALE` cookie docs to mention how it is used for redirecting from `/` more specifically. 

x-ref: https://github.com/vercel/next.js/pull/20045#discussion_r586158535

This ensures we load `_document` then `_app` and then the page's component in all cases which matches behavior between the serverless target and the default server target.  Additional tests to ensure this order is followed has been added to prevent regression. 

Fixes: https://github.com/vercel/next.js/issues/22732

@babel/plugin-proposal-class-properties is missing in with-mobx-react-lite example

I added this in to my own pipeline to fix the no-cache error and thought it may be of use to others.

This updates to output server chunks to a nested folder to prevent bundling the entire folder when tracing. This also fixes the webpack 5 tests not actually using webpack 5 since https://github.com/vercel/next.js/pull/22583 since the webpack 5 enabling check didn't account for the test environment variable used to enable webpack 5. This also clears up some deprecation warnings from webpack 5 in the mini-css-extract-plugin.

Fixes: https://github.com/vercel/next.js/issues/21297

 Making experimental script work in _document.js - Fixes for server to client transition
Adding additional test for _document.js

Help clarify that this option is available!

This avoids the warning when you init a new Next.js app with the example:

```
warn  - React 17.0.1 or newer will be required to leverage all of the upcoming features in Next.js 11. Read more: https://err.sh/next.js/react-version
```