From 23dee7c43f46b5cb8c3f1145461a93c4ca339d77 Mon Sep 17 00:00:00 2001
From: Sebastien Ros <sebastienros@gmail.com>
Date: Tue, 26 Feb 2019 17:15:23 -0800
Subject: [PATCH] Keep argument checks

---
 src/Razor/Razor/src/TagHelpers/NullHtmlEncoder.cs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/Razor/Razor/src/TagHelpers/NullHtmlEncoder.cs b/src/Razor/Razor/src/TagHelpers/NullHtmlEncoder.cs
index e7150a786b..be4b2d17c2 100644
--- a/src/Razor/Razor/src/TagHelpers/NullHtmlEncoder.cs
+++ b/src/Razor/Razor/src/TagHelpers/NullHtmlEncoder.cs
@@ -64,6 +64,21 @@ namespace Microsoft.AspNetCore.Razor.TagHelpers
 
         public override void Encode(TextWriter output, string value, int startIndex, int characterCount)
         {
+            if (output == null)
+            {
+                throw new ArgumentNullException(nameof(output));
+            }
+
+            if (value == null)
+            {
+                throw new ArgumentNullException(nameof(value));
+            }
+
+            if (characterCount == 0)
+            {
+                return;
+            }
+
             var span = value.AsSpan();
             output.Write(span.Slice(startIndex, characterCount));
         }