yep

Shogi.UI/Pages/Home/PageHeader.razor

@@ -5,10 +5,10 @@
     <h1>Shogi</h1>
     @if (user != null)
     {
-        <div class="user">
-            <div>@user.Value.DisplayName</div>
-            <button type="button" class="logout" @onclick="AccountManager.LogoutAsync">Logout</button>
-        </div>
+            <div class="user">
+                <div>@user.Value.DisplayName</div>
+                <button type="button" class="logout" @onclick="AccountManager.LogoutAsync">Logout</button>
+            </div>
     }
     @*<LoginDisplay />*@
 </div>
@@ -21,11 +21,12 @@
         Account.LoginChangedEvent += OnLoginChange;
     }
 
-    private void OnLoginChange(object? sender, LoginEventArgs args)
+    private Task OnLoginChange(LoginEventArgs args)
     {
         if (args == null)
             throw new ArgumentException(nameof(args));
         user = args.User;
         StateHasChanged();
+        return Task.CompletedTask;
     }
 }