Fix some bugs caused by order of operations.

Shogi.UI/Pages/Home/Account/AccountManager.cs

@@ -112,16 +112,17 @@ public class AccountManager
 
     public async Task LogoutAsync()
     {
-        await accountState.SetUser(null);
         var platform = await localStorage.GetAccountPlatform();
         await localStorage.DeleteAccountPlatform();
 
         if (platform == WhichAccountPlatform.Guest)
         {
             await shogiApi.GuestLogout();
+            await accountState.SetUser(null);
         }
         else if (platform == WhichAccountPlatform.Microsoft)
         {
+            await accountState.SetUser(null);
             navigation.NavigateToLogout("authentication/logout");
         }
     }