Blazor client side error

I performed this manual: and got an error:

When I added the attribute TItem="Product", this works, but I see:
Can you help how to solve this?

I’m not sure what is causing this issue. If you have a Radzen subscription you can send your project to

We managed to reproduce the problems. While we are not sure why the first issue happens yet we managed to fix the second (setting TItem as an attribute). We will continue investigating the first one.