I’m using dotnet with Open-AI’s official library,
I’ve wrote a service that sends an image and returns a JSON with specific structure, However, sometimes it response with a broken JSON object, which cause a server error..
How do I make it to response with a consist object structure ?

Here is the service I’ve wrote:

using System.Text.Json;
using backend.DTOs;
using OpenAI.Chat;

namespace backend.Services;

public class OpenAiService
{
    private readonly ChatClient _chatClient;
    private readonly ChatCompletionOptions _options;

    public OpenAiService(IConfiguration config)
    {
        var apiKey = config.GetValue<string>("OpenAI:Key");
        _chatClient = new ChatClient("gpt-4o", apiKey);
        _options = new ChatCompletionOptions()
        {
            MaxTokens = 300,
            ResponseFormat = ChatResponseFormat.JsonObject
        };
    }

    public async Task<ReceiptDto> ExtreactListOfItems(Stream imageStream)
    {
        var imageBytes = await BinaryData.FromStreamAsync(imageStream);

        var messages = new List<ChatMessage>
        {
            new UserChatMessage(
                new List<ChatMessageContentPart>
            {
                ChatMessageContentPart.CreateTextMessageContentPart(
                    @"
                    ""Extract a list of items from the following image, then return a list with each item to have a itemName itemPrice quantity totalItemPrice, return a json. ""
                        Make sure the following JSON response should look like:
                        {
                       ""storeName"": ""string"",
                        ""purchase"": {
                            ""purchaseDate"": ""2024-08-14T12:40:05.638Z"",
                            ""items"": [
                            {
                                ""itemName"": ""string"",
                                ""itemPrice"": 0,
                                ""quantity"": 0,
                               ""totalItemPrice"": 0
                                    }
                                ]
                            }
                        }."),
                ChatMessageContentPart.CreateImageMessageContentPart(imageBytes, "image/png")
            })
        };
        
        ChatCompletion completion = await _chatClient.CompleteChatAsync(messages, _options);

        var resp = completion.Content[0].ToString().Trim();
                
        Console.WriteLine("Raw Response: " + resp); 
        
        using var document = JsonDocument.Parse(resp);

        
        var receiptDto = JsonSerializer.Deserialize<ReceiptDto>(document.RootElement.GetRawText());
        
        Console.WriteLine("Deserialized Receipt: " + JsonSerializer.Serialize(receiptDto));

        return receiptDto;
    }
    
}