Fix several issues with multiplayer & playlists room join error logging

This is in response to
https://osu.ppy.sh/community/forums/topics/2058708?n=5, wherein the user
is having a problem with joining multiplayer, but I have basically no
diagnosing capabilities, because the logs are all

    2025-03-26 18:57:57 [error]: Failed to join multiplayer room:
    2025-03-26 18:58:40 [error]: Failed to join multiplayer room:
    2025-03-26 18:58:41 [error]: Failed to join multiplayer room:
    2025-03-26 18:58:41 [error]: Failed to join multiplayer room:

which appears to originate from

https://github.com/ppy/osu/blob/c82eaafe98d96b9f49a4a7f168ef5c484e67d76f/osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerLoungeSubScreen.cs#L91

Now, as far as I can tell, there are two possibilities here:

1. The exception's `Message` is null or empty. That's not exactly great
   or typical, but sure, this could possibly happen - in which case the
   error logging is silently eating whatever little relevant detail
   there is left to use.

2. The exception is *actually* `null` itself, and we're in the X Files.

This PR is intending to defend against (1).

In examining the logging further, I also spotted the following issues:

- In the single path that specifies a custom failure handler (which is
  `DrawableLoungeRoom` which handles joining a passworded room), the
  custom failure handler being present means that the error would be
  presented to the user, but it would not be logged. At all.

- In playlists, if the exception for whatever reason had an empty
  message, an empty notification would get posted. And in general to me
  it feels a bit dodgy to be directly presenting exception notifications
  to users without any preamble, hence the added "Failed to open
  playlist" prefix.

osu.Game.Tests/Visual/Multiplayer/TestSceneDrawableLoungeRoom.cs

@@ -40,7 +40,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
         {
             var mockLounge = new Mock<IOnlinePlayLounge>();
             mockLounge
-                .Setup(l => l.Join(It.IsAny<Room>(), It.IsAny<string>(), It.IsAny<Action<Room>>(), It.IsAny<Action<string>>()))
+                .Setup(l => l.Join(It.IsAny<Room>(), It.IsAny<string>(), It.IsAny<Action<Room>>(), It.IsAny<Action<string, Exception?>>()))
                 .Callback<Room, string, Action<Room>, Action<string>>((_, _, _, d) =>
                 {
                     Task.Run(() =>

osu.Game/Screens/OnlinePlay/Lounge/DrawableLoungeRoom.cs

@@ -17,6 +17,7 @@ using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
 using osu.Framework.Localisation;
+using osu.Framework.Logging;
 using osu.Game.Extensions;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Sprites;
@@ -306,13 +307,14 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
                 GetContainingFocusManager()?.TriggerFocusContention(passwordTextBox);
             }
 
-            private void joinFailed(string error) => Schedule(() =>
+            private void joinFailed(string message, Exception? exception) => Schedule(() =>
             {
                 passwordTextBox.Text = string.Empty;
 
                 GetContainingFocusManager()!.ChangeFocus(passwordTextBox);
 
-                errorText.Text = error;
+                Logger.Log($"Failed to join room with password. {exception}");
+                errorText.Text = message;
                 errorText
                     .FadeIn()
                     .FlashColour(Color4.White, 200)

osu.Game/Screens/OnlinePlay/Lounge/IOnlinePlayLounge.cs

@@ -14,8 +14,8 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
         /// <param name="room">The room to join.</param>
         /// <param name="password">The password.</param>
         /// <param name="onSuccess">A delegate to invoke if the user joined the room.</param>
-        /// <param name="onFailure">A delegate to invoke if the user is not able join the room.</param>
-        void Join(Room room, string? password, Action<Room>? onSuccess = null, Action<string>? onFailure = null);
+        /// <param name="onFailure">A delegate to invoke if the user is not able to join the room.</param>
+        void Join(Room room, string? password, Action<Room>? onSuccess = null, Action<string, Exception?>? onFailure = null);
 
         /// <summary>
         /// Copies the given room and opens it as a fresh (not-yet-created) one.

osu.Game/Screens/OnlinePlay/Lounge/LoungeSubScreen.cs

@@ -334,7 +334,7 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
             popoverContainer.HidePopover();
         }
 
-        public void Join(Room room, string? password, Action<Room>? onSuccess = null, Action<string>? onFailure = null) => Schedule(() =>
+        public void Join(Room room, string? password, Action<Room>? onSuccess = null, Action<string, Exception?>? onFailure = null) => Schedule(() =>
         {
             if (joiningRoomOperation != null)
                 return;
@@ -347,19 +347,19 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
                 joiningRoomOperation?.Dispose();
                 joiningRoomOperation = null;
                 onSuccess?.Invoke(room);
-            }, error =>
+            }, (message, exception) =>
             {
                 joiningRoomOperation?.Dispose();
                 joiningRoomOperation = null;
 
                 if (onFailure != null)
-                    onFailure(error);
+                    onFailure(message, exception);
                 else
-                    Logger.Log(error, level: LogLevel.Error);
+                    Logger.Error(exception, message);
             });
         });
 
-        protected abstract void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string> onFailure);
+        protected abstract void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string, Exception?> onFailure);
 
         public void OpenCopy(Room room)
         {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerLoungeSubScreen.cs

@@ -75,7 +75,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
 
         protected override OnlinePlaySubScreen CreateRoomSubScreen(Room room) => new MultiplayerMatchSubScreen(room);
 
-        protected override void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string> onFailure)
+        protected override void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string, Exception?> onFailure)
         {
             client.JoinRoom(room, password).ContinueWith(result =>
             {
@@ -86,9 +86,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
                     Exception? exception = result.Exception?.AsSingular();
 
                     if (exception?.GetHubExceptionMessage() is string message)
-                        onFailure(message);
+                        onFailure(message, exception);
                     else
-                        onFailure($"Failed to join multiplayer room: {exception?.Message}");
+                        onFailure($"Failed to join multiplayer room. {exception?.Message}", exception);
                 }
             });
         }

osu.Game/Screens/OnlinePlay/Playlists/PlaylistsLoungeSubScreen.cs

@@ -60,7 +60,7 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
             return criteria;
         }
 
-        protected override void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string> onFailure)
+        protected override void JoinInternal(Room room, string? password, Action<Room> onSuccess, Action<string, Exception?> onFailure)
         {
             var joinRoomRequest = new JoinRoomRequest(room, password);
 
@@ -68,7 +68,7 @@ namespace osu.Game.Screens.OnlinePlay.Playlists
             joinRoomRequest.Failure += exception =>
             {
                 if (exception is not OperationCanceledException)
-                    onFailure(exception.Message);
+                    onFailure($"Failed to open playlist. {exception.Message}", exception);
             };
 
             api.Queue(joinRoomRequest);