Extend RadzenGrid

Radzen.Blazor Components
1

Hi, I'm trying to extend functionality of RadzenGrid for my own purposes. What I'm trying to do (beside all other things) is to add RadzenFieldset around it, but this leads to a problem.

@inherits RadzenGrid<TItem>

<RadzenFieldset Text="@Name" style="margin: 10px;">
<div class="row">
    @{
        base.BuildRenderTree(__builder);
    }
</div>
</RadzenFieldset>

This throws an exception:
Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
Unhandled exception rendering component: Cannot read property 'parentNode' of undefined

But as soon as I move tree building outside of the fieldset/or I simply remove fieldset everything works fine.

@inherits RadzenGrid<TItem>

<div class="row">
    @{
        base.BuildRenderTree(__builder);
    }
</div>

I basically want to get rid of all the redundant code I have. But this is blocking me. Any ideas? Maybe I'm doing whole UI extension wrong?

Of course there is plenty of other things I extended - I want to use it as RadzenGrid but have some additional properties and functionality available. But only this rendering is causing the problem. Without Fieldset everything works like it should.