Core/Misc: A variety of clean-up changes:

Port From (https://github.com/TrinityCore/TrinityCore/commit/5aee452943e5c76f54f58eea9e6880b54a61ec9c)

Source/Game/AI/CoreAI/CreatureAI.cs

@@ -239,12 +239,12 @@ namespace Game.AI
 
                 return me.GetVictim() != null;
             }
-            else if (me.GetThreatManager().IsThreatListEmpty(true))
+            else if (!me.IsInCombat())
             {
                 EnterEvadeMode(EvadeReason.NoHostiles);
                 return false;
             }
-            else
+            else if (me.GetVictim() != null)
                 me.AttackStop();
 
             return true;

Source/Game/Chat/Commands/DebugCommands.cs

@@ -797,8 +797,6 @@ namespace Game.Chat
                 handler.SendSysMessage($"{target.GetName()} ({target.GetGUID()}) is not alive.");
                 return true;
             }
-            if (!target.CanHaveThreatList())
-                handler.SendSysMessage($"{target.GetName()} ({target.GetGUID()}) cannot have a threat list.");
 
             uint count = 0;
             var threatenedByMe = target.GetThreatManager().GetThreatenedByMeList();
@@ -816,9 +814,8 @@ namespace Game.Chat
             }
 
             if (!mgr.CanHaveThreatList())
-                return true;
-
-            if (mgr.IsEngaged())
+                handler.SendSysMessage($"{target.GetName()} ({target.GetGUID()}) cannot have a threat list.");
+            else if (mgr.IsEngaged())
             {
                 count = 0;
                 handler.SendSysMessage($"Threat list of {target.GetName()} ({target.GetGUID()}, SpawnID {(target.IsCreature() ? target.ToCreature().GetSpawnId() : 0)})");

Source/Game/Entities/Creature/Creature.cs

@@ -428,7 +428,7 @@ namespace Game.Entities
 
         public override void Update(uint diff)
         {
-            if (IsAIEnabled && triggerJustAppeared && m_deathState == DeathState.Alive)
+            if (IsAIEnabled && triggerJustAppeared && m_deathState != DeathState.Dead)
             {
                 if (m_respawnCompatibilityMode && VehicleKit != null)
                     VehicleKit.Reset();

Source/Game/Maps/Map.cs

@@ -2678,7 +2678,7 @@ namespace Game.Maps
         SpawnGroupTemplateData GetSpawnGroupData(uint groupId)
         {
             SpawnGroupTemplateData data = Global.ObjectMgr.GetSpawnGroupData(groupId);
-            if (data != null && data.mapId == GetId())
+            if (data != null && (data.flags.HasAnyFlag(SpawnGroupFlags.System) || data.mapId == GetId()))
                 return data;
 
             return null;
@@ -2812,13 +2812,14 @@ namespace Game.Maps
             SpawnGroupTemplateData data = GetSpawnGroupData(groupId);
             if (data == null)
             {
-                Log.outWarn(LogFilter.Maps, $"Tried to query state of non-existing spawn group {groupId} on map {GetId()}.");
+                Log.outError(LogFilter.Maps, $"Tried to query state of non-existing spawn group {groupId} on map {GetId()}.");
                 return false;
             }
 
             if (data.flags.HasAnyFlag(SpawnGroupFlags.System))
                 return true;
 
+            // either manual spawn group and toggled, or not manual spawn group and not toggled...
             return _toggledSpawnGroupIds.Contains(groupId) != !data.flags.HasAnyFlag(SpawnGroupFlags.ManualSpawn);
         }