Crash when applying damage.

[Chatouille]

Try this format instead :

if (HitActor && HitActor->Implements<UDamageable>())
{
    GEngine->AddOnScreenDebugMessage(-1, 0.1f, FColor::Cyan, "Hit an actor");

    // Call static Execute_ function with target object as first argument
    IDamageable::Execute_TakeDamage(HitActor, WeaponStats.Damage, OwningCharacter->GetController(), this);
}