Core/Aura: Replace assert with logged error for invalid AuraRemoveMode

Fix AuraScript::Remove() triggering an assert with default parameter and log an error when Aura is removed with invalid mode AURA_REMOVE_NONE instead of triggering an assert deep down in the call tree.
Fix https://github.com/TrinityCore/TrinityCore/issues/714 , triggered by spell 50240 "Evasive Maneuvers" script

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

@@ -3587,6 +3587,12 @@ void Unit::RemoveOwnedAura(Aura* aura, AuraRemoveMode removeMode)
 
     ASSERT(aura->GetOwner() == this);
 
+    if (removeMode == AURA_REMOVE_NONE)
+    {
+        TC_LOG_ERROR("spells", "Unit::RemoveOwnedAura() called with unallowed removeMode AURA_REMOVE_NONE, spellId %u", aura->GetId());
+        return;
+    }
+
     uint32 spellId = aura->GetId();
     AuraMapBoundsNonConst range = m_ownedAuras.equal_range(spellId);