Csharp 静态对象构造顺序

一般来说，我的理解是，类中的静态对象是在第一次引用类时构造的.然而，我正在经历一种我没有预料到的行为.

请考虑下面的类

public abstract class SmartColor<TColor> where TColor : SmartColor<TColor> {
    private static readonly ConcurrentDictionary<string, TColor> _items = new();

    protected SmartColor(string code, string name) {
        Code = code;
        Name = name;
        //register all colors
        foreach (var field in typeof(TColor).GetFields(BindingFlags.Public | BindingFlags.Static)) {
            TColor? item = (TColor?)field.GetValue(null);
            if (item is not null) {
                Register(item);
            }
        }
    }

    public string Code { get; }

    public string Name { get; }

    public static TColor FromCode(string code) {
        if (_items.TryGetValue(code, out var result)) {
            return result;
        }
        return null;
    }

    private void Register(TColor item) {
        _items.GetOrAdd(item.Code, item);
    }
}

它又是从这个继承而来的

public class WebColor : SmartColor<WebColor> {
    public static readonly WebColor White = new WebColor("#ffffff", nameof(White));
    public static readonly WebColor Black = new WebColor("#000000", nameof(Black));

    protected WebColor(string code, string name) : base(code, name) {
    }
}

如果按如下方式使用，它将生成NullReferenceException

public static void Main()
{
    WebColor color = WebColor.FromCode("#ffffff");
    Console.WriteLine(color.Name);
}

我能理解为什么会发生这种事吗？小提琴here