Add notnull to guard

Author: stefannikolei

src/SharedInfrastructure/DebugGuard.cs

@@ -2,6 +2,7 @@
 // Licensed under the Six Labors Split License.
 
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 
 namespace SixLabors;
@@ -22,14 +23,9 @@ internal static partial class DebugGuard
     /// <typeparam name="TValue">The type of the value.</typeparam>
     /// <exception cref="ArgumentNullException"><paramref name="value"/> is null.</exception>
     [Conditional("DEBUG")]
-    public static void NotNull<TValue>(TValue value, string parameterName)
-        where TValue : class
-    {
-        if (value is null)
-        {
-            ThrowArgumentNullException(parameterName);
-        }
-    }
+    public static void NotNull<TValue>([NotNull] TValue? value, string parameterName)
+        where TValue : class =>
+        ArgumentNullException.ThrowIfNull(value,parameterName);
 
     /// <summary>
     /// Ensures that the target value is not null, empty, or whitespace.