On an Exception in Scene.RemoveClient(), always remove the client (and SP) structure so that logout on unexpired packets isn't retriggered, causing the same exception

OpenSim/Region/Framework/Scenes/Scene.cs

@@ -3104,6 +3104,8 @@ namespace OpenSim.Region.Framework.Scenes
                     // Avatar is already disposed :/
                 }
 
+                try
+                {
                     m_eventManager.TriggerOnRemovePresence(agentID);
     
                     if (AttachmentsModule != null && !avatar.IsChildAgent && avatar.PresenceType != PresenceType.Npc)
@@ -3122,10 +3124,17 @@ namespace OpenSim.Region.Framework.Scenes
                     {
                         agentTransactions.RemoveAgentAssetTransactions(agentID);
                     }
-
+                }
-                // Remove the avatar from the scene
+                finally
+                {
+                    // Always clean these structures up so that any failure above doesn't cause them to remain in the
+                    // scene with possibly bad effects (e.g. continually timing out on unacked packets and triggering
+                    // the same cleanup exception continually.
+                    // TODO: This should probably extend to the whole method, but we don't want to also catch the NRE
+                    // since this would hide the underlying failure and other associated problems.
                     m_sceneGraph.RemoveScenePresence(agentID);
                     m_clientManager.Remove(agentID);
+                }
 
                 try
                 {