[BUG] TypeValidationError on User for certain old broken beatmaps with deleted set owners

[EnricoBaivo]

Describe the bug
Im receiving an Error for fetching a Beatmapset that doesn't contain all the expected fields
To Reproduce
Steps to reproduce the behavior:

1. use beatmapset_id =19378
2. Get get_beatmapset(19378)

beatmapset_id = 19378

    @prepare_token
    @check_token
    @requires_scope(Scopes.PUBLIC)
    async def get_beatmapset(self, beatmapset_id: int) -> Beatmapset:
        r"""Get beatmapset data.
    
        :param beatmapset_id: The ID of the beatmapset
        :type beatmapset_id: int
        :raises APIException: Contains status code and error message
        :raises RefreshTokenExpiredError: If the client refresh token has expired
        :return: Beatmapset data object
        :rtype: aiosu.models.beatmap.Beatmapset
        """
        url = f"{self.base_url}/api/v2/beatmapsets/{beatmapset_id}"
        json = await self._request("GET", url)
>       return Beatmapset.model_validate(json)
E       pydantic_core._pydantic_core.ValidationError: 3 validation errors for Beatmapset
E       user.avatar_url
E         Input should be a valid string [type=string_type, input_value=None, input_type=NoneType]
E           For further information visit https://errors.pydantic.dev/2.7/v/string_type
E       user.country_code
E         Input should be a valid string [type=string_type, input_value=None, input_type=NoneType]
E           For further information visit https://errors.pydantic.dev/2.7/v/string_type
E       user.id
E         Input should be a valid integer [type=int_type, input_value=None, input_type=NoneType]
E           For further information visit https://errors.pydantic.dev/2.7/v/int_type
´´´
**Expected behavior**
the Beatmapset should be correctly returned

[NiceAesth]

cannot repro

this is more of an osu-web issue though (which i assume they have since fixed?)