From ed2a1f519476bf357c1ce5c5d9e2ac6360ba8e58 Mon Sep 17 00:00:00 2001
From: Stevan Freeborn <65925598+StevanFreeborn@users.noreply.github.com>
Date: Thu, 2 Apr 2026 20:49:11 -0500
Subject: [PATCH] fix: add null guard to WithCustomCryptoProvider in
 SecureConfigBuilder

---
 .../Configuration/SecureConfigBuilder.cs               | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/StevanFreeborn.Extensions.Configuration.Secure/Configuration/SecureConfigBuilder.cs b/src/StevanFreeborn.Extensions.Configuration.Secure/Configuration/SecureConfigBuilder.cs
index cba3650..b248bdf 100644
--- a/src/StevanFreeborn.Extensions.Configuration.Secure/Configuration/SecureConfigBuilder.cs
+++ b/src/StevanFreeborn.Extensions.Configuration.Secure/Configuration/SecureConfigBuilder.cs
@@ -91,12 +91,20 @@ internal sealed class SecureConfigBuilder : ISecureConfigBuilder
 
   public ISecureConfigBuilder WithAesCryptoProvider()
   {
-    CryptoProviderFactory = (kp) => new AesCryptoProvider(kp);
+    CryptoProviderFactory = keyProvider => new AesCryptoProvider(keyProvider);
     return this;
   }
 
   public ISecureConfigBuilder WithCustomCryptoProvider(Func<IEncryptionKeyProvider, ICryptoProvider> cryptoProviderFactory)
   {
+#if NET6_0_OR_GREATER
+    ArgumentNullException.ThrowIfNull(cryptoProviderFactory);
+#else
+    if (cryptoProviderFactory is null)
+    {
+      throw new ArgumentNullException(nameof(cryptoProviderFactory));
+    }
+#endif
     CryptoProviderFactory = cryptoProviderFactory;
     return this;
   }