fix(possess): don't destroy caster in Apply; defer possession to OnJumpCompleted to prevent PawnFlyer NRE

- CompAbilityEffect_Possess.Apply now only logs; DoPossession runs after landing
- Harden HediffComp_GestaltNode against null/destroyed pawn (tick/severity/overlord search/relations)
- Fix GestaltOverseer Notify_PostRemovedByDeath message condition (only when overlord died/destroyed and hive node alive)

Source/ArachnaeSwarm/Hediffs/ARA_GestaltNode/HediffComp_GestaltNode.cs

@@ -35,7 +35,13 @@ namespace ArachnaeSwarm
         {
             get
             {
-                CompGestalt comp = Pawn.TryGetComp<CompGestalt>();
+                var pawn = Pawn;
+                if (pawn == null)
+                {
+                    return tracker;
+                }
+
+                CompGestalt comp = pawn.TryGetComp<CompGestalt>();
                 if (comp != null)
                 {
                     return comp.GestaltTracker;
@@ -43,7 +49,7 @@ namespace ArachnaeSwarm
                  
                 if (tracker == null && NodeType == GestaltNodeType.OverlordNode)
                 {
-                    tracker = new Pawn_GestaltTracker(Pawn);
+                    tracker = new Pawn_GestaltTracker(pawn);
                 }
                 return tracker;
             }
@@ -60,6 +66,12 @@ namespace ArachnaeSwarm
         {
             base.CompPostTick(ref severityAdjustment);
 
+            var pawn = Pawn;
+            if (pawn == null)
+            {
+                return;
+            }
+            
             if (NodeType == GestaltNodeType.HiveNode)
             {
                 // 定期更新严重性
@@ -69,9 +81,9 @@ namespace ArachnaeSwarm
                 }
                 
                 // 定期寻找 OverlordNode
-                if (Pawn.IsColonist &&
+                if (pawn.IsColonist &&
-                    Pawn.Spawned &&
+                    pawn.Spawned &&
-                    !Pawn.Dead &&
+                    !pawn.Dead &&
                     Find.TickManager.TicksGame % 250 == 0)
                 {
                     TryFindOverlord();
@@ -87,6 +99,12 @@ namespace ArachnaeSwarm
             if (NodeType != GestaltNodeType.HiveNode || parent == null)
                 return;
 
+            var pawn = Pawn;
+            if (pawn?.health == null)
+            {
+                return;
+            }
+                
             bool isConnected = IsConnectedToOverlord();
             
             // 只有连接状态改变时才更新，避免每帧都设置
@@ -103,7 +121,7 @@ namespace ArachnaeSwarm
                 wasConnected = isConnected;
                 
                 // 如果严重性改变，需要重新计算Pawn的能力
-                Pawn.health.Notify_HediffChanged(parent);
+                pawn.health.Notify_HediffChanged(parent);
             }
         }
         
@@ -118,6 +136,12 @@ namespace ArachnaeSwarm
         public void TryFindOverlord()
         {
             // 如果已经有Overlord，更新连接状态并返回
+            var pawn = Pawn;
+            if (pawn == null || pawn.Dead || pawn.Destroyed)
+            {
+                return;
+            }
+
             if (IsConnectedToOverlord())
             {
                 UpdateSeverityBasedOnConnection();
@@ -125,7 +149,7 @@ namespace ArachnaeSwarm
             }
             
             // 如果Pawn当前不在地图上，无法寻找Overlord
-            if (Pawn.Map == null)
+            if (pawn.Map == null)
             {
                 return;
             }
@@ -134,22 +158,23 @@ namespace ArachnaeSwarm
             Pawn bestOverlord = null;
             float bestScore = -1f;
             
-            foreach (Pawn pawn in Pawn.Map.mapPawns.FreeColonists)
+            foreach (Pawn candidate in pawn.Map.mapPawns.FreeColonists)
             {
-                HediffComp_GestaltNode nodeComp = pawn.GetGestaltNodeComp();
+                HediffComp_GestaltNode nodeComp = candidate.GetGestaltNodeComp();
                 if (nodeComp?.NodeType == GestaltNodeType.OverlordNode &&
-                    pawn != Pawn &&
+                    candidate != pawn &&
-                    !pawn.Dead &&
+                    !candidate.Dead &&
-                    !pawn.Downed)
+                    !candidate.Downed &&
+                    !candidate.Destroyed)
                 {
-                    Pawn_GestaltTracker tracker = pawn.GestaltTracker();
+                    Pawn_GestaltTracker tracker = candidate.GestaltTracker();
-                    if (tracker != null && tracker.CanControlPawn(Pawn))
+                    if (tracker != null && tracker.CanControlPawn(pawn))
                     {
-                        float score = CalculateOverlordScore(pawn, tracker);
+                        float score = CalculateOverlordScore(candidate, tracker);
                         if (score > bestScore)
                         {
                             bestScore = score;
-                            bestOverlord = pawn;
+                            bestOverlord = candidate;
                         }
                     }
                 }
@@ -158,7 +183,11 @@ namespace ArachnaeSwarm
             // 找到合适的Overlord，建立关系并更新严重性
             if (bestOverlord != null)
             {
-                Pawn.relations.AddDirectRelation(ARA_PawnRelationDefOf.ARA_GestaltOverseer, bestOverlord);
+                // Pawns being destroyed/vanished can temporarily have no relations tracker.
+                if (pawn.relations != null && ARA_PawnRelationDefOf.ARA_GestaltOverseer != null)
+                {
+                    pawn.relations.AddDirectRelation(ARA_PawnRelationDefOf.ARA_GestaltOverseer, bestOverlord);
+                }
                 UpdateSeverityBasedOnConnection();
             }
         }
@@ -188,10 +217,16 @@ namespace ArachnaeSwarm
             // 当Hediff被移除时，如果连接到Overlord，需要断开连接
             if (NodeType == GestaltNodeType.HiveNode && IsConnectedToOverlord())
             {
-                Pawn overlord = Pawn.GetOverlord();
+                var pawn = Pawn;
+                if (pawn?.relations == null || ARA_PawnRelationDefOf.ARA_GestaltOverseer == null)
+                {
+                    return;
+                }
+
+                Pawn overlord = pawn.GetOverlord();
                 if (overlord != null)
                 {
-                    Pawn.relations.RemoveDirectRelation(ARA_PawnRelationDefOf.ARA_GestaltOverseer, overlord);
+                    pawn.relations.RemoveDirectRelation(ARA_PawnRelationDefOf.ARA_GestaltOverseer, overlord);
                 }
             }
         }

Source/ArachnaeSwarm/Hediffs/ARA_GestaltNode/PawnRelationWorker_GestaltOverseer.cs

@@ -83,7 +83,7 @@ namespace ArachnaeSwarm
                 }
             }
             
-            if (overlord != null && hiveNode != null && (!overlord.Dead || overlord.Destroyed))
+            if (overlord != null && hiveNode != null && !hiveNode.Dead && (overlord.Dead || overlord.Destroyed))
             {
                 Messages.Message("MessageGestaltLostControl".Translate(overlord, hiveNode) + ": " + hiveNode.LabelShortCap,
                     new LookTargets(new Thing[] { overlord, hiveNode }), MessageTypeDefOf.NeutralEvent);