Channel update event handler: log ArgumentExceptions in more detail

Tasks/EventTasks.cs

@@ -111,7 +111,18 @@ await Program.db.HashSetAsync("overrides", userOverwrites.Name,
 
                                     if (dict is not null)
                                     {
-                                        dict.Add(e.ChannelAfter.Id, overwrite);
+                                        try
+                                        {
+                                            dict.Add(e.ChannelAfter.Id, overwrite);
+                                        }
+                                        catch (ArgumentException ex)
+                                        {
+                                            Program.discord.Logger.LogWarning(ex, "Failed to process pending channel update event for channel {channel}: failed to add overwrite with ID {id} to db", e.ChannelAfter.Id, overwrite.Id);
+
+                                            // Skip this overwrite
+                                            PendingChannelUpdateEvents.Remove(timestamp);
+                                            continue;
+                                        }
 
                                         if (dict.Count > 0)
                                             await Program.db.HashSetAsync("overrides", overwrite.Id,