Fix failed to load beatmap detail host by deleted user

[EYHN]

I found that the current version cannot open the beatmap detail created by a deleted account.

This bug is introduced by #33783 .

The reason is that user.id in the JSON returned by osu-web is null, which causes the APIUser fail to deserialize.

Because the Id of APIUser is int, it cannot be null.
I don't want to change Id to int?, so in this PR i added NullValueHandling.Ignore to it. This way, null values will be ignored during deserialize, and Id will still retain its default value (i.e. 1)

[smoogipoo]

Can you link a relevant beatmap? And also add a test case for this in TestSceneBeatmapSetOverlay, even if it's just deserialising a raw JSON string?

[EYHN]

Can you link a relevant beatmap?

https://osu.ppy.sh/beatmapsets/25

And also add a test case for this in TestSceneBeatmapSetOverlay, even if it's just deserialising a raw JSON string?

I didn't find any other test cases for deserialising raw JSON that I could refer to. It's a pretty complex json and I'm not sure if I should be doing this.

Maybe we should have a deserialization test? Because this time the issue is in from Deserializer.

The original response:

APIBeatmapSet.json

[smoogipoo]

The part I was interested in a test for was for how it actually displays with a user-id of 1.

I was thinking you could do something like this:

[Test]
public void TestDeletedUser()
{
    AddStep("show map with deleted user", () =>
    {
        JObject jsonBlob = JObject.FromObject(getBeatmapSet(), new JsonSerializer
        {
            ReferenceLoopHandling = ReferenceLoopHandling.Ignore
        });

        jsonBlob["user"] = JToken.Parse(
            """
            {
                "id": null,
                "username": "[deleted user]"
            }
            """);

        overlay.ShowBeatmapSet(JsonConvert.DeserializeObject<APIBeatmapSet>(JsonConvert.SerializeObject(jsonBlob)));
    });
}

Though you'll have to set a few more properties - perhaps jsonBlob.Remove("user_id") and others. That's why I wanted the raw JSON to reference.

[EYHN]

I have added a test, and I adjusted the author field in APIBeatmapSet.

Now the BeatmapSet detail will shows the username of the deleted account, which is consistent with the web.

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