Circuit Error using RadzenDropDown

I am getting a circuit error using the RadzenDropDown. Below is a simplification that throws the error.

Object Not Set To An Instance of an object. I had to enable SignalR debugging.

It occurs when I click a button to show the form for adding a row.

I kept removing code until I got the code below.

Any ideas on what else to check or how else to debug.

   protected IEnumerable<Manufacturer> Manufacturers { get; set; } = new List<Manufacturer>();
   protected override async Task OnInitializedAsync()
      brand = new Brand();
<RadzenDropDown Data="@Manufacturers" TextProperty="Name" ValueProperty="Id" AllowClear=true Placeholder="Choose Manufacturer" style="display: block; width: 100%" @bind-Value="@brand.Manufacturer.Id" Name="ManufacturerId" /> *@

This is null reference exception, you can check the stack trace for reference.

The problem happens because brand is null at first. Same thing will happen if you just output @brand.Manufacturer.Id. The solution is to add an if check before using something that can be null.