依赖关系注入和 C# 中的保护子句和空对象模式

使用构造函数注入，依赖项被注入到这样的消费者中（至少我希望我理解正确）：

public class SomeConsumer
{
    private IDependency someDependency;
    public SomeConsumer(IDependency someDependency)
    {
        if (someDependency != null)
        {
            this.someDependency = someDependency;
        }
        else
        {
            throw new ArgumentNullException("someDependency");
        }
    }
    public void Baz()
    {
        someDependency.DoSomething();
    }
    (...)
}

如果我使用 Null 对象模式进行 IDependency，我是否需要保护子句？还是注入空对象是错误的？

更新：为了澄清，让我们假设我有这样的类和接口：

public interface IDependency
{
    void DoSomething();
}
public class NullDependency : IDependency
{
    public void DoSomething()
    {
        //Do nothing...
    }
}
public class RealDependency : IDependency
{
    public void DoSomething()
    {
        Console.WriteLine("Did something");
    }
}
public class Foo
{
    public void Bar()
    {
        IDependency dependency = new NullDependency();
        SomeConsumer sc = new SomeConsumer(dependency);
        sc.Baz();
    }
}

然后，我是否可以安全地从 SomeConsumer 中删除保护子句，使其看起来像：

public class SomeConsumer
{
    private IDependency someDependency;
    public SomeConsumer(IDependency someDependency)
    {
        this.someDependency = someDependency;
    }
    public void Baz()
    {
        //if someDependency is a NullDependency, this does nothing
        someDependency.DoSomething(); 
    }
    (...)
}

还是我应该使用保护条款，因为我不能确定null永远不会被注入？