Code Inspection: Possible 'System.NullReferenceException'

ReSharper analyzes nullability of symbols and issues a warning if it detects access to members on objects that can be null references.

Note that nullability analysis is configurable, meaning that you can define in which situations ReSharper will assume values to be null references.

You can find detailed explanations of how ReSharper detects possible 'null' dereferences in Value and Nullability Analysis and Detect Possible NullReferenceExceptions topics.