WithPerTenantAuthentication Causes NullReferenceException in Blazor Web App with the default Individual Accounts Authentication

[cozalp]

Hello! I am encountering an issue while integrating Finbuckle.MultiTenant in a Blazor application using the standard "Blazor Web App" template of .NET 8, with "Individual Accounts" authentication type in Server render mode.

Following the documentation, I added the multi-tenant services as shown below:

builder.Services.AddMultiTenant<AppTenantInfo>()
    .WithHostStrategy()
    .WithConfigurationStore()
    .WithPerTenantAuthentication();

However, using WithPerTenantAuthentication() results in the following exception:

fail: Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
      An unhandled exception has occurred while executing the request.
      System.NullReferenceException: Object reference not set to an instance of an object.
         at lambda_method91(Closure, QueryContext)
         at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, Expression expression, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, LambdaExpression expression, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.FirstOrDefaultAsync[TSource](IQueryable`1 source, Expression`1 predicate, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserOnlyStore`6.FindByNameAsync(String normalizedUserName, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Identity.UserManager`1.FindByNameAsync(String userName)
         at Microsoft.AspNetCore.Identity.SignInManager`1.PasswordSignInAsync(String userName, String password, Boolean isPersistent, Boolean lockoutOnFailure)
         at BlazorApp_FinbuckleMultitenantTest.Components.Account.Pages.Login.LoginUser() in D:\tests\BlazorApp_FinbuckleMultitenantTest\BlazorApp_FinbuckleMultitenantTest\Components\Account\Pages\Login.razor:line 92
         at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
         at Microsoft.AspNetCore.Components.Forms.EditForm.HandleSubmitAsync()
         at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
         at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
         at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)
         at Microsoft.AspNetCore.Components.Endpoints.EndpointHtmlRenderer.<WaitForNonStreamingPendingTasks>g__Execute|38_0()
         at Microsoft.AspNetCore.Components.Endpoints.RazorComponentEndpointInvoker.RenderComponentCore(HttpContext context)
         at Microsoft.AspNetCore.Components.Endpoints.RazorComponentEndpointInvoker.RenderComponentCore(HttpContext context)
         at Microsoft.AspNetCore.Components.Rendering.RendererSynchronizationContext.<>c.<<InvokeAsync>b__10_0>d.MoveNext()
      --- End of stack trace from previous location ---
         at Microsoft.AspNetCore.Antiforgery.Internal.AntiforgeryMiddleware.InvokeAwaited(HttpContext context)
         at Finbuckle.MultiTenant.AspNetCore.Internal.MultiTenantMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
         at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

Additionally, when WithPerTenantAuthentication() is removed, login works, however account related pages with for example UserManager gives the following exception:

   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ExecuteAsync[TSource,TResult](MethodInfo operatorMethodInfo, IQueryable`1 source, LambdaExpression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.FirstOrDefaultAsync[TSource](IQueryable`1 source, Expression`1 predicate, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Internal.EntityFinder`1.FindAsync(Object[] keyValues, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.FindAsync(Object[] keyValues, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserOnlyStore`6.FindByIdAsync(String userId, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Identity.UserManager`1.GetUserAsync(ClaimsPrincipal principal)
   at BlazorApp_FinbuckleMultitenantTest.Components.Account.IdentityUserAccessor.<GetRequiredUserAsync>d__3.MoveNext() in D:\tests\BlazorApp_FinbuckleMultitenantTest\BlazorApp_FinbuckleMultitenantTest\Components\Account\IdentityUserAccessor.cs:line 10

Example Repository:

A minimal reproduction of the issue can be found here: BlazorApp_FinbuckleMultitenantTest

I have tried various troubleshooting steps but have not been able to resolve the issue. Any help or guidance would be greatly appreciated.