var item throwing exception when tested against null

I am seeing some strange behaviour testing for null value against a var type using C#.NET

Here is some sample code.

//  locate user in cache

var user = GWUsers.Instance.Users.Where(u => u.EmailAddress == emailAddress).FirstOrDefault();

if (user != null)
{

} 

When the user contains a null value an exception is thrown indicating that the "object reference is not set".

GWUsers is a singleton used to hold a list of users stored in an XML file. This very same piece of code is used throughout the application, but in this one instance, it throws an exception when evaluated against a null.

Any ide开发者_如何学JAVAas why that might be?

Appreciate any insight on this.

Thanks

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Very likely the following could be the reasons:

• GWUsers.Instance.Users is null
• One of the instances in the list is null

---

In the case of a null user element within Users, you could modify the LINQ statement to the following:

GWUsers.Instance.Users.Where(u => u != null && u.EmailAddress == u.mailAddress).FirstOrDefault();`

It would not help with Users being null, however.