If you are using `response_model` with some type that doesn't include `None` but the function is returning `None`, it will now raise an internal server error, because you are returning invalid data that violates the contract in `response_model`. Before this release it would allow breaking that contract returning `None`.

For example, if you have an app like this:

```Python
from fastapi import FastAPI

* Fix incorrectly propagated ResourceVersion in ListRequests returning 0 items. ([#64150](https://github.com/kubernetes/kubernetes/pull/64150), [@wojtek-t](https://github.com/wojtek-t))

protobuf you will be forced to restore from backup, and you will lose any changes
since you converted to protobuf.  After conversion to protobuf, you should
validate the correct operation of your cluster thoroughly before returning it
to normal operation.

Backups are always a good precaution, particularly around upgrades, but this
upgrade has multiple known issues where the only remedy is to restore from
backup.

- Kube-apiserver: fixed a bug returning inconsistent results from list requests which set a field or label selector and set a paging limit ([#94002](https://github.com/kubernetes/kubernetes/pull/94002), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]

* Protobuf serialization does not distinguish between `[]` and `null`. ([#45294](https://github.com/kubernetes/kubernetes/pull/45294), [@liggitt](https://github.com/liggitt))

- Kube-apiserver: fixed a bug returning inconsistent results from list requests which set a field or label selector and set a paging limit ([#94002](https://github.com/kubernetes/kubernetes/pull/94002), [@wojtek-t](https://github.com/wojtek-t)) [SIG API Machinery]

Type inference supports calls of generic functions and assignments
of generic functions to (explicitly function-typed) variables.
This includes passing generic functions as arguments to other
(possibly also generic) functions, and returning generic functions
as results.
Type inference operates on a set of equations specific to each of
these cases.
The equations are as follows (type argument lists are omitted for clarity):
</p>

<ul>

   ([#123003](https://github.com/kubernetes/kubernetes/pull/123003), [@alexzielenski](https://github.com/alexzielenski))
- Fixed a non-recursive list returning "resource version too high" error when consistent listing from cache is enabled.
   ([#123674](https://github.com/kubernetes/kubernetes/pull/123674), [@serathius](https://github.com/serathius))

`Interrupted(error) bool` helper to replace checks for `err == ErrWaitTimeout`, or compare specifically to context errors as needed. A future release will make the `ErrWaitTimeout` error private and callers must use `Interrupted()` instead. If you are returning `ErrWaitTimeout` from your own methods, switch to creating a location specific `cause err` and pass it to the new method `wait.ErrorInterrupted(cause) error` which will ensure `Interrupted()` returns true for your loop. 
  
  The `wa...

- Fixed recursive LIST from watch cache returning object matching key. ([#125584](https://github.com/kubernetes/kubernetes/pull/125584), [@serathius](https://github.com/serathius)) [SIG API Machinery and Testing]