Fix WhereTests.FirstElementWithQueryThatReturnsNoResults test

Author: hazzik

src/NHibernate.Test/Linq/WhereTests.cs

@@ -70,7 +70,7 @@ public void FirstElementWithQueryThatReturnsNoResults()
 
 			Assert.Throws<InvalidOperationException>(() =>
 				{
-					users.ToList();
+					users.First();
 				});
 		}