DRF don't raise 404 error when the url is not found

[mojixcoder]

When I include router.urls in my app.
Everything is fine when urls are called correctly.
But when I call an non-existing URL I don't get 404 error, and I get 500 instead.

Here is my error:

for permission in self.get_permissions():
TypeError: 'NoneType' object is not iterable
[04/Oct/2021 16:33:58] "POST /api/v1/accounts/asdads/ HTTP/1.1" 500 102626

It's clear that there is no action for this url!!!
and when I comment this method i get 401 instead because all of my pages are IsAuthenticated by default.
When I call .../v1/accounts/blablbalba/ I get 500.

Here is my urls.py:

from django.urls import path, include

from rest_framework.routers import DefaultRouter
from rest_framework_simplejwt.views import TokenRefreshView

from api.v1.account.apis import UserViewSet


router = DefaultRouter()

router.register("", UserViewSet, basename="user")

urlpatterns = [
    # V1 APIs
    path("v1/accounts/refresh/", TokenRefreshView().as_view(), name="refresh"),
    path("v1/accounts/", include(router.urls)),
]

And It is my apis.py:

class UserViewSet(ModelViewSet):
    """# User View Set

    **endpoints:**<br/>
    <code>
    / post -> signup <br/>
    / get -> list <br/>
    / get <int:id> -> retrieve <br/>
    /login post -> send opt code for user <br/>
    /verify post -> login verification <br/>
    </code>
    """
    serializer_classes = {
        "list": UserReadOnlySerializer,
        "retrieve": UserReadOnlySerializer,
        "create": UserReadOnlySerializer,
        "login": LoginSerializer,
        "verify": VerifySerializer,
    }
    permissions = {
        "list": [IsAuthenticated(), IsAdmin()],
        "retrieve": [IsAuthenticated(), IsAdmin()],
        "create": [AllowAny()],
        "login": [IsNotAuthenticated()],
        "verify": [IsNotAuthenticated()],
    }
    http_method_names = ["get", "post"]

    def get_serializer_class(self):
        return self.serializer_classes[self.action]

    def get_permissions(self):
        return self.permissions.get(self.action)

    def get_queryset(self):
        users = user_cache_manager.get_all()
        return users

[tomchristie]

Seems like the issue is that your custom get_permissions method is returning None in some cases...

You'll probably need to change your code to something like this...

    def get_permissions(self):
        return self.permissions.get(self.action, default=[])

[mojixcoder]

So what about non existing urls ?
How to raise 404?
Is it ok for 'self.action' to be None ?