MSAL Authentication - WASM Web application - Failed to construct URL

I need you clever peoples help.

I need to get msal authentication working with EntraID. I have a net 6 wasm application and I am getting daft errors - I must have looked at my appsettings.json file 100 times for a typo.

I am getting the error :

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]Unhandled exception rendering component: Failed to construct 'URL': Invalid URLTypeError: Failed to construct 'URL': Invalid URLat new u (https://localhost:7151/_content/Microsoft.Authentication.WebAssembly.Msal/AuthenticationService.js:2:191011)at l.init (https://localhost:7151/_content/Microsoft.Authentication.WebAssembly.Msal/AuthenticationService.js:2:196273)

My web app to get the msal working as very very basic indeed, nothing special here.Appsettings.json file

Index.html

<div id="blazor-error-ui">    An unhandled error has occurred.<a href="" class="reload">Reload</a><a class="dismiss">🗙</a></div><script src="_framework/blazor.webassembly.js"></script><script src="_content/Microsoft.Authentication.WebAssembly.Msal/AuthenticationService.js"></script>

Program.cs

using AuthWebApp;using Microsoft.AspNetCore.Components.Web;using Microsoft.AspNetCore.Components.WebAssembly.Hosting;var builder = WebAssemblyHostBuilder.CreateDefault(args);builder.RootComponents.Add<App>("#app");builder.RootComponents.Add<HeadOutlet>("head::after");builder.Services.AddScoped(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });builder.Services.AddMsalAuthentication(options =>{    builder.Configuration.Bind("AzureAd", options.ProviderOptions.Authentication);    options.ProviderOptions.LoginMode = "redirect";});await builder.Build().RunAsync();

index.razor

@page "/"<PageTitle>Index</PageTitle>@attribute [Authorize]<h1>User needs to be in AD for this page to work</h1>

Authentication.razor

@page "/Authentication/{action}"@using Microsoft.AspNetCore.Components.WebAssembly.Authentication<RemoteAuthenticatorView Action="@action"></RemoteAuthenticatorView>@code {    [Parameter] public string ?action { get; set; }}

I cannot seem to get over this error and the logging is pretty useless on the browser. THe app registration is just a basic one with the redirect set to :

https://localhost:7151/Authentication/login-callback

anyone with any quick ideas ?