Core: Corrected NULL usage, it should only be used with pointers, not integers

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -4525,9 +4525,8 @@ void AuraEffect::HandleAuraModStateImmunity(AuraApplication const * aurApp, uint
     Unit * target = aurApp->GetTarget();
 
     if ((apply) && GetSpellProto()->AttributesEx & SPELL_ATTR1_DISPEL_AURAS_ON_IMMUNITY)
-    {
-        target->RemoveAurasByType(AuraType(GetMiscValue()), NULL , GetBase());
-    }
+        target->RemoveAurasByType(AuraType(GetMiscValue()), 0 , GetBase());
+
     // stop handling the effect if it was removed by linked event
     if (apply && aurApp->GetRemoveMode())
         return;

src/server/game/Spells/SpellMgr.h

@@ -1371,7 +1371,7 @@ class SpellMgr
             SpellRequiredMap::const_iterator itr = mSpellReq.find(spell_id);
 
             if (itr == mSpellReq.end())
-                return NULL;
+                return 0;
 
             return itr->second;
         }

src/server/game/Spells/SpellScript.cpp

@@ -348,7 +348,7 @@ int32 SpellScript::GetHitDamage()
     if (!IsInHitPhase())
     {
         sLog->outError("TSCR: Script: `%s` Spell: `%u`: function SpellScript::GetHitDamage was called while spell not in hit phase!", m_scriptName->c_str(), m_scriptSpellId);
-        return NULL;
+        return 0;
     }
     return m_spell->m_damage;
 }
@@ -368,7 +368,7 @@ int32 SpellScript::GetHitHeal()
     if (!IsInHitPhase())
     {
         sLog->outError("TSCR: Script: `%s` Spell: `%u`: function SpellScript::GetHitHeal was called while spell not in hit phase!", m_scriptName->c_str(), m_scriptSpellId);
-        return NULL;
+        return 0;
     }
     return m_spell->m_healing;
 }