NullReferenceException when using JsonSetAsync with CommandFlags.FireAndForget

[jordankasper11]

I apologize if I'm overlooking something obvious, but I'm new to RedisJSON and am running into an issue while trying to do a pretty simple task. I'm trying to generate some sample products and add them to Redis, but I get a NullReferenceException when executing the following code:

var multiplexer = await ConnectionMultiplexer.ConnectAsync("localhost");
var redis = multiplexer.GetDatabase();

var departments = new string[] { "Men", "Women", "Kids", "Travel", "Electronics" };
var brands = new string[] { "Apple", "Microsoft", "Samsung", "Sony", "Nike", "Adidas", "Reebok" };
var colors = new string[] { "Black", "Blue", "Green", "Grey", "Orange", "Pink", "Purple", "Red", "White" };
var random = new Random();

var count = 0;

while (count < 1000000)
{
    var tasks = new List<Task>();

    while (tasks.Count < 10000)
    {
        count++;

        var product = new
        {
            Id = $"product-{count}",
            Department = departments.GetValue(random.Next(0, departments.Length)),
            Brand = brands.GetValue(random.Next(0, brands.Length)),
            Color = colors.GetValue(random.Next(0, colors.Length)),
            Name = $"Product {count}",
            Description = "<p>Sed interdum aliquet augue eget placerat. Aliquam ac orci placerat, mattis arcu quis, finibus est. Aenean erat purus, dignissim in dapibus ut, eleifend nec nunc.</p>",
            Price = Math.Round((0.01 + random.NextDouble()) * 250, 2)
        };

        var task = redis.JsonSetAsync(product.Id, product, commandFlags: CommandFlags.FireAndForget);

        tasks.Add(task);
    }

    await Task.WhenAll(tasks);
}

The error is triggered by this line of code:

var task = redis.JsonSetAsync(product.Id, product, commandFlags: CommandFlags.FireAndForget);

I can eliminate the error by replacing this line with either of the following:

var task = redis.JsonSetAsync(product.Id, product);

or

var json = JsonSerializer.Serialize(product);
var task = redis.SetAddAsync(product.Id, json, CommandFlags.FireAndForget);

I want to keep CommandFlags.FireAndForget as it is much faster, but it seems that combining this with NReJSON doesn't work.

If it makes any difference, this is my SerializerProxy:

public sealed class RedisJsonSerializer : ISerializerProxy
{
    public TResult Deserialize<TResult>(RedisResult serializedValue)
    {
        return JsonSerializer.Deserialize<TResult>(serializedValue.ToString());
    }

    public string Serialize<TObjectType>(TObjectType obj)
    {
        return JsonSerializer.Serialize(obj);
    }
}

Any assistance would be greatly appreciated. Thanks!