DoesNotExist: User matching query does not exist.

https://app.getsentry.com/nightcrawler/backend/issues/135540106/

```
DoesNotExist: User matching query does not exist.
  File "extras/views.py", line 49, in profile
    user = User.objects.get(pk=pk)

DoesNotExist: User matching query does not exist.
```

just need to `get_object_or_404`
