add IsEffect() check to correct IsImmunedToSpell

Signed-off-by: dr.skull <dr.skull@centrum.sk>

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

@@ -11534,10 +11534,12 @@ bool Unit::IsImmunedToSpell(SpellInfo const* spellInfo)
     }
 
     bool immuneToAllEffects = true;
-    for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
+    for (uint32 i = 0; i < MAX_SPELL_EFFECTS; ++i)
     {
         // State/effect immunities applied by aura expect full spell immunity
         // Ignore effects with mechanic, they are supposed to be checked separately
+        if(!spellInfo->Effects[i].IsEffect())
+            break;
         if (!IsImmunedToSpellEffect(spellInfo, i))
         {
             immuneToAllEffects = false;