Core/Units: added a helper to check if a limited target aura exists without creating an empty element in the container

src/server/game/Entities/Unit/Unit.cpp

@@ -4339,6 +4339,16 @@ void Unit::_ApplyAllAuraStatMods()
         (*i).second->GetBase()->HandleAllEffects(i->second, AURA_EFFECT_HANDLE_STAT, true);
 }
 
+bool Unit::HasLimitedTargetAuraForSpell(uint32 spellId) const
+{
+    AurasBySpellIdMap::const_iterator itr = m_ltAuras.find(spellId);
+
+    if (itr == m_ltAuras.end())
+        return false;
+
+    return !itr->second.empty();
+}
+
 AuraEffect* Unit::GetAuraEffect(uint32 spellId, uint8 effIndex, ObjectGuid caster) const
 {
     AuraApplicationMapBounds range = m_appliedAuras.equal_range(spellId);

src/server/game/Entities/Unit/Unit.h

@@ -1403,6 +1403,7 @@ class TC_GAME_API Unit : public WorldObject
         AuraEffectList const& GetAuraEffectsByType(AuraType type) const { return m_modAuras[type]; }
         AuraList& GetLimitedCastAuras(uint32 spellId) { return m_ltAuras[spellId]; }
         AurasBySpellIdMap& GetAllLimitedCastAuras() { return m_ltAuras; }
+        bool HasLimitedTargetAuraForSpell(uint32 spellId) const;
 
         AuraEffect* GetAuraEffect(uint32 spellId, uint8 effIndex, ObjectGuid casterGUID = ObjectGuid::Empty) const;
         AuraEffect* GetAuraEffectOfRankedSpell(uint32 spellId, uint8 effIndex, ObjectGuid casterGUID = ObjectGuid::Empty) const;

src/server/scripts/Spells/spell_mage.cpp

@@ -982,7 +982,7 @@ class spell_mage_nether_vortex : public AuraScript
 
     bool CheckProc(ProcEventInfo& /*eventInfo*/)
     {
-        return GetTarget()->GetLimitedCastAuras(SPELL_MAGE_SLOW).empty();
+        return GetTarget()->HasLimitedTargetAuraForSpell(SPELL_MAGE_SLOW);
     }
 
     void HandleEffectProc(AuraEffect const* aurEff, ProcEventInfo& eventInfo)