Correct middleware order for UseSpa() from Microsoft.AspNetCore.SpaServices.Extensions

Program.cs

var builder = WebApplication.CreateBuilder();
builder.Services.AddFastEndpoints();

var app = builder.Build();
app.UseRouting(); //should be before auth/cors/fastendpoints middlewares.
app.UseAuthorization();
app.UseFastEndpoints();
app.UseEndpoints(_ => { }); //should be right after UseFastEndpoints(). this is the terminating middleware for endpoint routes.

if (app.Environment.IsDevelopment())
    app.UseSpa(x => x.UseProxyToSpaDevelopmentServer("http://localhost:8001"));

app.Run();