Added some additional defense checks around isHostile and unit/target (#2056)

Needs second pair of eyes, they appear in crash logs here and there. Its
merely a patch on a open wound.

----
As in aslong there multithreads in mapupdate, which we need for decent
performance and core calls are not done correctly due various reasons.
These type of issues remain.

Although i am planning to experiment a little with threadsafe execution
of our strategies vs performance.

The most effective thing we could do is check every single action and
check its stateless and where it does effect the state or read the state
of a core object its done in the safest way. flags, worldthread where
possible and/ot simply taking into account the state might be invalid.

src/Ai/Base/Actions/TravelAction.cpp

@@ -28,7 +28,7 @@ bool TravelAction::Execute(Event event)
     for (Unit* unit : targets)
     {
         newTarget = unit;
-        if (!newTarget)
+        if (!newTarget || !newTarget->IsInWorld() || newTarget->IsDuringRemoveFromWorld())
             continue;
 
         if (newTarget->GetMapId() != bot->GetMapId())

src/Ai/Base/Actions/UseItemAction.cpp

@@ -245,8 +245,10 @@ bool UseItemAction::UseItem(Item* item, ObjectGuid goGuid, Item* itemTarget, Uni
         {
             packet << unitTarget->GetGUID();
             targetSelected = true;
-            // If the target is bot or is an enemy, say "on self"
+
-            if (unitTarget == bot || (unitTarget->IsHostileTo(bot)))
+            if (unitTarget == bot || !unitTarget->IsInWorld() || unitTarget->IsDuringRemoveFromWorld())
+                out << " on self";
+            else if (unitTarget->IsHostileTo(bot))
                 out << " on self";
             else
                 out << " on " << unitTarget->GetName();

src/Ai/Base/Value/AttackersValue.cpp

@@ -258,6 +258,9 @@ bool PossibleAddsValue::Calculate()
 
         if (Unit* add = botAI->GetUnit(guid))
         {
+            if (!add->IsInWorld() || add->IsDuringRemoveFromWorld())
+                continue;
+
             if (!add->GetTarget() && !add->GetThreatMgr().getCurrentVictim() && add->IsHostileTo(bot))
             {
                 for (ObjectGuid const attackerGUID : attackers)

src/Ai/Base/Value/GrindTargetValue.cpp

@@ -59,26 +59,22 @@ Unit* GrindTargetValue::FindTargetForGrinding(uint32 assistCount)
     for (ObjectGuid const guid : targets)
     {
         Unit* unit = botAI->GetUnit(guid);
-
         if (!unit)
             continue;
 
+        if (!unit->IsInWorld() || unit->IsDuringRemoveFromWorld())
+            continue;
+
         auto& rep = bot->ToPlayer()->GetReputationMgr();
         if (unit->ToCreature() && !unit->ToCreature()->GetCreatureTemplate()->lootid &&
             bot->GetReactionTo(unit) >= REP_NEUTRAL)
-        {
             continue;
-        }
 
         if (!bot->IsHostileTo(unit) && unit->GetNpcFlags() != UNIT_NPC_FLAG_NONE)
-        {
             continue;
-        }
 
         if (!bot->isHonorOrXPTarget(unit))
-        {
             continue;
-        }
 
         if (abs(bot->GetPositionZ() - unit->GetPositionZ()) > INTERACTION_DISTANCE)
             continue;

src/Ai/Base/Value/NearestNpcsValue.cpp

@@ -27,7 +27,16 @@ void NearestHostileNpcsValue::FindUnits(std::list<Unit*>& targets)
     Cell::VisitObjects(bot, searcher, range);
 }
 
-bool NearestHostileNpcsValue::AcceptUnit(Unit* unit) { return unit->IsHostileTo(bot) && !unit->IsPlayer(); }
+bool NearestHostileNpcsValue::AcceptUnit(Unit* unit)
+{
+    if (!unit || !unit->IsInWorld() || unit->IsDuringRemoveFromWorld())
+        return false;
+
+    if (unit->IsPlayer())
+        return false;
+
+    return unit->IsHostileTo(bot);
+}
 
 void NearestVehiclesValue::FindUnits(std::list<Unit*>& targets)
 {

src/Ai/Base/Value/PossibleRpgTargetsValue.cpp

@@ -54,6 +54,9 @@ void PossibleRpgTargetsValue::FindUnits(std::list<Unit*>& targets)
 
 bool PossibleRpgTargetsValue::AcceptUnit(Unit* unit)
 {
+    if (!unit || !unit->IsInWorld() || unit->IsDuringRemoveFromWorld())
+        return false;
+
     if (unit->IsHostileTo(bot) || unit->IsPlayer())
         return false;
 
@@ -70,7 +73,8 @@ bool PossibleRpgTargetsValue::AcceptUnit(Unit* unit)
     }
 
     TravelTarget* travelTarget = context->GetValue<TravelTarget*>("travel target")->Get();
-    if (travelTarget->getDestination() && travelTarget->getDestination()->getEntry() == unit->GetEntry())
+    if (travelTarget && travelTarget->getDestination() &&
+        travelTarget->getDestination()->getEntry() == unit->GetEntry())
         return true;
 
     if (urand(1, 100) < 25 && unit->IsFriendlyTo(bot))
@@ -145,6 +149,9 @@ void PossibleNewRpgTargetsValue::FindUnits(std::list<Unit*>& targets)
 
 bool PossibleNewRpgTargetsValue::AcceptUnit(Unit* unit)
 {
+    if (!unit || !unit->IsInWorld() || unit->IsDuringRemoveFromWorld())
+        return false;
+
     if (unit->IsHostileTo(bot) || unit->IsPlayer())
         return false;
 

src/Ai/Raid/Icecrown/Trigger/RaidIccTriggers.cpp

@@ -99,7 +99,10 @@ bool IccGunshipCannonNearTrigger::IsActive()
 bool IccGunshipTeleportAllyTrigger::IsActive()
 {
     Unit* boss = bot->FindNearestCreature(NPC_HIGH_OVERLORD_SAURFANG, 100.0f);
-    if (!boss)
+    if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
+        return false;
+
+    if (!boss->IsAlive())
         return false;
 
     if (!boss->IsHostileTo(bot))
@@ -111,7 +114,10 @@ bool IccGunshipTeleportAllyTrigger::IsActive()
 bool IccGunshipTeleportHordeTrigger::IsActive()
 {
     Unit* boss = bot->FindNearestCreature(NPC_MURADIN_BRONZEBEARD, 100.0f);
-    if (!boss)
+    if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
+        return false;
+
+    if (!boss->IsAlive())
         return false;
 
     if (!boss->IsHostileTo(bot))

src/Ai/Raid/Ulduar/Trigger/RaidUlduarTriggers.cpp

@@ -765,9 +765,13 @@ bool FreyaMoveToHealingSporeTrigger::IsActive()
 bool ThorimUnbalancingStrikeTrigger::IsActive()
 {
     Unit* boss = AI_VALUE2(Unit*, "find target", "thorim");
+    if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
+        return false;
 
-    // Check boss and it is alive
+    if (!boss->IsAlive())
-    if (!boss || !boss->IsAlive() || !boss->IsHostileTo(bot))
+        return false;
+
+    if (!boss->IsHostileTo(bot))
         return false;
 
     return bot->HasAura(SPELL_UNBALANCING_STRIKE);
@@ -804,8 +808,13 @@ bool ThorimMarkDpsTargetTrigger::IsActive()
 
         Unit* boss = AI_VALUE2(Unit*, "find target", "thorim");
 
-        // Check boss and it is alive
+        if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
-        if (!boss || !boss->IsAlive() || !boss->IsHostileTo(bot))
+            return false;
+
+        if (!boss->IsAlive())
+            return false;
+
+        if (!boss->IsHostileTo(bot))
             return false;
 
         if (boss->GetPositionZ() < ULDUAR_THORIM_AXIS_Z_FLOOR_THRESHOLD && (!currentSkullUnit || !currentSkullUnit->IsAlive()))
@@ -982,9 +991,13 @@ bool ThorimGauntletPositioningTrigger::IsActive()
 bool ThorimArenaPositioningTrigger::IsActive()
 {
     Unit* boss = AI_VALUE2(Unit*, "find target", "thorim");
+    if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
+        return false;
 
-    // Check boss and it is alive
+    if (!boss->IsAlive())
-    if (!boss || !boss->IsAlive() || !boss->IsHostileTo(bot))
+        return false;
+
+    if (!boss->IsHostileTo(bot))
         return false;
 
     if (boss->GetPositionZ() < ULDUAR_THORIM_AXIS_Z_FLOOR_THRESHOLD)
@@ -1080,9 +1093,13 @@ bool ThorimPhase2PositioningTrigger::IsActive()
         return false;
 
     Unit* boss = AI_VALUE2(Unit*, "find target", "thorim");
+    if (!boss || !boss->IsInWorld() || boss->IsDuringRemoveFromWorld())
+    return false;
 
-    // Check boss and it is alive
+    if (!boss->IsAlive())
-    if (!boss || !boss->IsAlive() || !boss->IsHostileTo(bot))
+        return false;
+
+    if (!boss->IsHostileTo(bot))
         return false;
 
     if (boss->GetPositionZ() > ULDUAR_THORIM_AXIS_Z_FLOOR_THRESHOLD)