When working with Blazor and clipboard, you might get following exception
DOMException: Document is not focused
or
JSException: Document is not focused
The exception is typically thrown when writeText or readText JS functions are invoked.
await _jsRuntime.InvokeVoidAsync("navigator.clipboard.writeText", text);
This exception happen if you have set some breakpoint in Blazor code or you have opened the debugging tools window.