Protect against requests to show overlays before the target overlay is ready

osu.Game/OsuGame.cs

@@ -215,16 +215,20 @@ private void load(FrameworkConfigManager frameworkConfig)
 
         private ExternalLinkOpener externalLinkOpener;
 
-        public void HandleLink(string url) => HandleLink(MessageFormatter.GetLinkDetails(url));
+        /// <summary>
+        /// Handle an arbitrary URL. Displays via in-game overlays where possible.
+        /// This can be called from a non-thread-safe non-game-loaded state.
+        /// </summary>
+        /// <param name="url">The URL to load.</param>
+        public void HandleLink(string url) => Schedule(() => HandleLink(MessageFormatter.GetLinkDetails(url)));
 
+        /// <summary>
+        /// Handle a specific <see cref="LinkDetails"/>.
+        /// This can be called from a non-thread-safe non-game-loaded state.
+        /// </summary>
+        /// <param name="link">The link to load.</param>
         public void HandleLink(LinkDetails link)
         {
-            Action showNotImplementedError = () => notifications?.Post(new SimpleNotification
-            {
-                Text = @"This link type is not yet supported!",
-                Icon = FontAwesome.Solid.LifeRing,
-            });
-
             switch (link.Action)
             {
                 case LinkAction.OpenBeatmap:
@@ -239,21 +243,17 @@ public void HandleLink(LinkDetails link)
                     break;
 
                 case LinkAction.OpenChannel:
-                    try
-                    {
-                        channelManager.OpenChannel(link.Argument);
-                    }
-                    catch (ChannelNotFoundException)
-                    {
-                        Logger.Log($"The requested channel \"{link.Argument}\" does not exist");
-                    }
-
+                    ShowChannel(link.Argument);
                     break;
 
                 case LinkAction.OpenEditorTimestamp:
                 case LinkAction.JoinMultiplayerMatch:
                 case LinkAction.Spectate:
-                    showNotImplementedError.Invoke();
+                    waitForReady(() => notifications, _ => notifications?.Post(new SimpleNotification
+                    {
+                        Text = @"This link type is not yet supported!",
+                        Icon = FontAwesome.Solid.LifeRing,
+                    }));
                     break;
 
                 case LinkAction.External:
@@ -270,31 +270,47 @@ public void HandleLink(LinkDetails link)
             }
         }
 
-        public void OpenUrlExternally(string url)
+        public void OpenUrlExternally(string url) => waitForReady(() => externalLinkOpener, _ =>
         {
             if (url.StartsWith("/"))
                 url = $"{API.Endpoint}{url}";
 
             externalLinkOpener.OpenUrlExternally(url);
-        }
+        });
+
+        /// <summary>
+        /// Open a specific channel in chat.
+        /// </summary>
+        /// <param name="channel">The channel to display.</param>
+        public void ShowChannel(string channel) => waitForReady(() => channelManager, _ =>
+        {
+            try
+            {
+                channelManager.OpenChannel(channel);
+            }
+            catch (ChannelNotFoundException)
+            {
+                Logger.Log($"The requested channel \"{channel}\" does not exist");
+            }
+        });
 
         /// <summary>
         /// Show a beatmap set as an overlay.
         /// </summary>
         /// <param name="setId">The set to display.</param>
-        public void ShowBeatmapSet(int setId) => beatmapSetOverlay.FetchAndShowBeatmapSet(setId);
+        public void ShowBeatmapSet(int setId) => waitForReady(() => beatmapSetOverlay, _ => beatmapSetOverlay.FetchAndShowBeatmapSet(setId));
 
         /// <summary>
         /// Show a user's profile as an overlay.
         /// </summary>
         /// <param name="userId">The user to display.</param>
-        public void ShowUser(long userId) => userProfile.ShowUser(userId);
+        public void ShowUser(long userId) => waitForReady(() => userProfile, _ => userProfile.ShowUser(userId));
 
         /// <summary>
         /// Show a beatmap's set as an overlay, displaying the given beatmap.
         /// </summary>
         /// <param name="beatmapId">The beatmap to show.</param>
-        public void ShowBeatmap(int beatmapId) => beatmapSetOverlay.FetchAndShowBeatmap(beatmapId);
+        public void ShowBeatmap(int beatmapId) => waitForReady(() => beatmapSetOverlay, _ => beatmapSetOverlay.FetchAndShowBeatmap(beatmapId));
 
         /// <summary>
         /// Present a beatmap at song select immediately.
@@ -452,6 +468,23 @@ private void performFromMainMenu(Action action, string taskName, Type targetScre
             performFromMainMenuTask = Schedule(() => performFromMainMenu(action, taskName));
         }
 
+        /// <summary>
+        /// Wait for the game (and target component) to become loaded and then run an action.
+        /// </summary>
+        /// <param name="retrieveInstance">A function to retrieve a (potentially not-yet-constructed) target instance.</param>
+        /// <param name="action">The action to perform on the instance when load is confirmed.</param>
+        /// <typeparam name="T">The type of the target instance.</typeparam>
+        private void waitForReady<T>(Func<T> retrieveInstance, Action<T> action)
+            where T : Drawable
+        {
+            var instance = retrieveInstance();
+
+            if (ScreenStack == null || ScreenStack.CurrentScreen is StartupScreen || instance?.IsLoaded != true)
+                Schedule(() => waitForReady(retrieveInstance, action));
+            else
+                action(instance);
+        }
+
         protected override void Dispose(bool isDisposing)
         {
             base.Dispose(isDisposing);