❔ Implementing RoleStore/RoleManager

System.NullReferenceException: 'Object reference not set to an instance of an object.'

roleStore was null.

using (var scope = app.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                var context = services.GetRequiredService<ApplicationDbContext>();
                UserManager<Account>? userManager = services.GetService<UserManager<Account>>();
                var roleStore = services.GetService<RoleStore<IdentityRole>>();
                var roleManager = services.GetService<RoleManager<Account>>();

                // Create my user.
                var user = new Account { UserName = "foo", Email = "foo" };
                var password = "foo";
                await userManager.CreateAsync(user, password);

                // Create role(s).
                var rolea = new IdentityRole { Name = "Blogger" };
                var roleb = new IdentityRole { Name = "Discusser" };
                var rolec = new IdentityRole { Name = "Planner" };

                // Insert role(s) into "RoleStore".
                var roleTasks = new Task[] {
                    roleStore.CreateAsync(rolea),
                    roleStore.CreateAsync(roleb),
                    roleStore.CreateAsync(rolec)
                };
                await Task.WhenAll(roleTasks);

                // Assign the role(s) to my user.
                await userManager.AddToRoleAsync(user, "Blogger");
                await userManager.AddToRoleAsync(user, "Discusser");
                await userManager.AddToRoleAsync(user, "Planner");
            }

//builder.Services.AddScoped<IRoleStore<IdentityRole>, RoleStore<IdentityRole>>();