Fix for null RequestOptions

Author: joseharriaga

src/Custom/Chat/ChatClient.cs

@@ -138,7 +138,7 @@ protected internal ChatClient(ClientPipeline pipeline, string model, OpenAIClien
     /// <exception cref="ArgumentException"> <paramref name="messages"/> is an empty collection, and was expected to be non-empty. </exception>
     public virtual Task<ClientResult<ChatCompletion>> CompleteChatAsync(IEnumerable<ChatMessage> messages, ChatCompletionOptions options = null, CancellationToken cancellationToken = default)
     {
-        return CompleteChatAsync(messages, options, cancellationToken.ToRequestOptions());
+        return CompleteChatAsync(messages, options, cancellationToken.ToRequestOptions() ?? new RequestOptions());
     }
 
     internal async Task<ClientResult<ChatCompletion>> CompleteChatAsync(IEnumerable<ChatMessage> messages, ChatCompletionOptions options, RequestOptions requestOptions)

src/Custom/Responses/OpenAIResponseClient.cs

@@ -121,7 +121,7 @@ protected internal OpenAIResponseClient(ClientPipeline pipeline, string model, O
 
     public virtual Task<ClientResult<OpenAIResponse>> CreateResponseAsync(IEnumerable<ResponseItem> inputItems, ResponseCreationOptions options = null, CancellationToken cancellationToken = default)
     {
-        return CreateResponseAsync(inputItems, options, cancellationToken.ToRequestOptions());
+        return CreateResponseAsync(inputItems, options, cancellationToken.ToRequestOptions() ?? new RequestOptions());
     }
 
     internal async Task<ClientResult<OpenAIResponse>> CreateResponseAsync(IEnumerable<ResponseItem> inputItems, ResponseCreationOptions options, RequestOptions requestOptions)