Core/Scripts: Added NULL checks to new target selectors, threat references aren't guaranteed to be valid always, also added (default true) player typeid check to NonTankTargetSelector

src/server/game/AI/CoreAI/UnitAI.cpp

@@ -255,6 +255,9 @@ SpellTargetSelector::SpellTargetSelector(Unit* caster, uint32 spellId) :
 
 bool SpellTargetSelector::operator()(Unit const* target) const
 {
+    if (!target)
+        return false;
+
     if (_spellInfo->CheckTarget(_caster, target) != SPELL_CAST_OK)
         return false;
 
@@ -289,5 +292,11 @@ bool SpellTargetSelector::operator()(Unit const* target) const
 
 bool NonTankTargetSelector::operator()(Unit const* target) const
 {
+    if (!target)
+        return false;
+
+    if (_playerOnly && target->GetTypeId() != TYPEID_PLAYER)
+        return false;
+
     return target != _source->getVictim();
 }

src/server/game/AI/CoreAI/UnitAI.h

@@ -116,11 +116,12 @@ struct SpellTargetSelector : public std::unary_function<Unit*, bool>
 struct NonTankTargetSelector : public std::unary_function<Unit*, bool>
 {
     public:
-        explicit NonTankTargetSelector(Creature* source) : _source(source) { }
+        NonTankTargetSelector(Creature* source, bool playerOnly = true) : _source(source), _playerOnly(playerOnly) { }
         bool operator()(Unit const* target) const;
 
     private:
         Creature const* _source;
+        bool _playerOnly;
 };
 
 class UnitAI