Core/Spells: You should be able to revive pets from anywhere without summoning them first

Closes #1090
Signed-off-by: Subv <s.v.h21@hotmail.com>

src/server/game/Spells/Spell.cpp

@@ -5238,10 +5238,8 @@ SpellCastResult Spell::CheckCast(bool strict)
             case SPELL_EFFECT_SUMMON_DEAD_PET:
             {
                 Creature* pet = m_caster->GetGuardianPet();
-                if (!pet)
-                    return SPELL_FAILED_NO_PET;
 
-                if (pet->isAlive())
+                if (pet && pet->isAlive())
                     return SPELL_FAILED_ALREADY_HAVE_SUMMON;
 
                 break;
@@ -5291,7 +5289,6 @@ SpellCastResult Spell::CheckCast(bool strict)
 
                 if (m_caster->GetCharmGUID())
                     return SPELL_FAILED_ALREADY_HAVE_CHARM;
-
                 break;
             }
             case SPELL_EFFECT_SUMMON_PLAYER: