From 2ceab1dc56cef75983b4c3f8b741d601702531f4 Mon Sep 17 00:00:00 2001
From: "Collin M. Barrett" <collinbarrett@users.noreply.github.com>
Date: Wed, 3 Jul 2019 10:44:57 -0500
Subject: [PATCH] throw exception on null argument of
 IReadOnlyList<T>.FirstOrDefault()

---
 .../Extensions/ReadOnlyListExtensions.cs                 | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/FilterLists.Agent/Extensions/ReadOnlyListExtensions.cs b/src/FilterLists.Agent/Extensions/ReadOnlyListExtensions.cs
index 093fc24fc..101ca01b0 100644
--- a/src/FilterLists.Agent/Extensions/ReadOnlyListExtensions.cs
+++ b/src/FilterLists.Agent/Extensions/ReadOnlyListExtensions.cs
@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 
 namespace FilterLists.Agent.Extensions
 {
@@ -6,9 +7,9 @@ public static class ReadOnlyListExtensions
     {
         public static T FirstOrDefault<T>(this IReadOnlyList<T> list)
         {
-            if (list is null || list.Count == 0)
-                return default;
-            return list[0];
+            if (list is null)
+                throw new ArgumentNullException(nameof(list));
+            return list.Count == 0 ? default : list[0];
         }
     }
 }
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