Address PR feedback

Author: stephentoub

src/Libraries/Microsoft.Extensions.AI/ChatCompletion/FunctionInvokingChatClient.cs

@@ -584,7 +584,7 @@ FunctionResultContent CreateFunctionResultContent(FunctionInvocationResult resul
             startingTimestamp = Stopwatch.GetTimestamp();
             if (_logger.IsEnabled(LogLevel.Trace))
             {
-                LogInvokingSensitive(context.Function.Metadata.Name, LoggingHelpers.AsJson(context.CallContent.Arguments));
+                LogInvokingSensitive(context.Function.Metadata.Name, LoggingHelpers.AsJson(context.CallContent.Arguments, context.Function.Metadata.JsonSerializerOptions));
             }
             else
             {
@@ -629,7 +629,7 @@ FunctionResultContent CreateFunctionResultContent(FunctionInvocationResult resul
 
                 if (result is not null && _logger.IsEnabled(LogLevel.Trace))
                 {
-                    LogInvocationCompletedSensitive(context.Function.Metadata.Name, elapsed, LoggingHelpers.AsJson(result));
+                    LogInvocationCompletedSensitive(context.Function.Metadata.Name, elapsed, LoggingHelpers.AsJson(result, context.Function.Metadata.JsonSerializerOptions));
                 }
                 else
                 {

src/Libraries/Microsoft.Extensions.AI/LoggingHelpers.cs

@@ -11,9 +11,8 @@ internal static class LoggingHelpers
     /// <summary>Serializes <paramref name="value"/> as JSON for logging purposes.</summary>
     public static string AsJson<T>(T value, JsonSerializerOptions? options = null)
     {
-        options ??= AIJsonUtilities.DefaultOptions;
-
-        if (options.TryGetTypeInfo(typeof(T), out var typeInfo))
+        if (options?.TryGetTypeInfo(typeof(T), out var typeInfo) is true ||
+            AIJsonUtilities.DefaultOptions.TryGetTypeInfo(typeof(T), out typeInfo))
         {
             return JsonSerializer.Serialize(value, typeInfo);
         }