fix: avoid switching to non-existent linkshell idx

Prevents switching channels to a non-existent linkshell index (for both
regular linkshells and cross-world linkshells). ExtraChat linkshells are
already validated separately.

Prevents ChatLogWindow Draw failures from causing ChatTwo to grab input
focus each frame if the exception occurs during an Activate event.

ChatTwo/GameFunctions/Chat.cs

@@ -312,6 +312,36 @@ internal sealed unsafe class Chat : IDisposable
     //     EurekaContextMenuTellHook!.Original(a1, playerName, worldName, worldId, accountId, contentId, reason);
     // }
 
+    /// <summary>
+    /// Returns true if the channel is any non-linkshell channel, or if the
+    /// linkshell actually exists.
+    /// </summary>
+    internal static bool ValidAnyLinkshell(InputChannel channel)
+    {
+        var idx = channel.LinkshellIndex();
+        if (idx == uint.MaxValue || channel.IsExtraChatLinkshell())
+            return true;
+        if (channel.IsLinkshell() && ValidLinkshell(idx))
+            return true;
+        if (channel.IsCrossLinkshell() && ValidCrossLinkshell(idx))
+            return true;
+        return false;
+    }
+
+    internal static bool ValidLinkshell(uint idx)
+    {
+        if (idx > 7)
+            return false;
+        return InfoProxyLinkshell.Instance()->LinkShells[(int) idx].Id != 0;
+    }
+
+    internal static bool ValidCrossLinkshell(uint idx)
+    {
+        if (idx > 7)
+            return false;
+        return InfoProxyCrossWorldLinkshell.Instance()->CrossWorldLinkshells[(int) idx].Name.Length > 0;
+    }
+
     internal static void SetChannel(InputChannel channel, string? tellTarget = null)
     {
         // ExtraChat linkshells aren't supported in game so we never want to
@@ -326,6 +356,8 @@ internal sealed unsafe class Chat : IDisposable
         var idx = channel.LinkshellIndex();
         if (idx == uint.MaxValue)
             idx = 0;
+        if (!ValidAnyLinkshell(channel))
+            return;
 
         RaptureShellModule.Instance()->ChangeChatChannel((int) channel, idx, target, true);
         target->Dtor(true);

ChatTwo/GameFunctions/KeybindManager.cs

@@ -9,6 +9,7 @@ using Dalamud.Utility.Signatures;
 using FFXIVClientStructs.FFXIV.Client.System.String;
 using FFXIVClientStructs.FFXIV.Client.UI;
 using ImGuiNET;
+using ModifierFlag = ChatTwo.GameFunctions.Types.ModifierFlag;
 
 namespace ChatTwo.GameFunctions;
 

ChatTwo/Ui/ChatLogWindow.cs

@@ -172,6 +172,9 @@ public sealed class ChatLogWindow : Window
 
         if (info.Channel != null)
         {
+            if (!GameFunctions.Chat.ValidAnyLinkshell(info.Channel.Value))
+                return;
+
             var prevTemp = TempChannel;
             if (info.Permanent)
                 SetChannel(info.Channel.Value);
@@ -206,11 +209,21 @@ public sealed class ChatLogWindow : Window
             if (info.Channel is InputChannel.Linkshell1 && info.Rotate != RotateMode.None)
             {
                 var idx = GameFunctions.Chat.RotateLinkshellHistory(mode);
+                if (idx < 0 || !GameFunctions.Chat.ValidLinkshell((uint)idx))
+                {
+                    TempChannel = 0;
+                    return;
+                }
                 TempChannel = info.Channel.Value + (uint) idx;
             }
             else if (info.Channel is InputChannel.CrossLinkshell1 && info.Rotate != RotateMode.None)
             {
                 var idx = GameFunctions.Chat.RotateCrossLinkshellHistory(mode);
+                if (idx < 0 || !GameFunctions.Chat.ValidCrossLinkshell((uint)idx))
+                {
+                    TempChannel = 0;
+                    return;
+                }
                 TempChannel = info.Channel.Value + (uint) idx;
             }
         }
@@ -480,10 +493,19 @@ public sealed class ChatLogWindow : Window
 
     public override void Draw()
     {
-        DrawChatLog();
+        try
-
+        {
-        AddPopOutsToDraw();
+            DrawChatLog();
-        DrawAutoComplete();
+            AddPopOutsToDraw();
+            DrawAutoComplete();
+        }
+        catch (Exception e)
+        {
+            Plugin.Log.Error($"Error drawing Chat Log window: {e}");
+            // Prevent recurring draw failures from constantly trying to grab
+            // input focus, which breaks every other ImGui window.
+            Activate = false;
+        }
     }
 
     private static bool IsChatMode => Plugin.Config.PreviewPosition is PreviewPosition.Inside or PreviewPosition.Tooltip;