Is this an analyzer bug?

Rider keeps telling me that Null refs are possible but I don't see how.

class Class1
{
    internal enum Enum1
    {
        Case0,
        Case1,
        Case2,
    }

    internal Enum1 EnumField { get; set; }

    [CanBeNull]
    internal Class1 ClassField { get; set; }

    public void Test()
    {
        if (EnumField != Enum1.Case0)
        {
            if (ClassField == null) throw new Exception();
        }

        switch (EnumField)
        {
            case Enum1.Case0:
                break;
            case Enum1.Case1:
                ClassField.Test(); // Possible null ref?
                break;
            case Enum1.Case2:
                ClassField.Test(); // Possible null ref?
                break;
            default:
                throw new ArgumentOutOfRangeException();
        }
    }
}