It's always better to face weapon charges then end up dead...
If it happened in the parking lot would that still count as pertaining to concealed carry in a bar serving liquor? I mean, I know it would indicate that you had your weapon in the establishment, but a good lawyer could probably get you around that. Nevertheless, If my life is ever in danger, I'll shoot first then deal with the red tape issues after my attacker is permanently down.
CG4U, Ch. 46.035 of the Penal Code is a bit ambiguous since it says, "premises," and not much else. However, case law and opinions issued by the TABC have made it pretty clear that premises includes the parking lot, exterior buildings, and other structures/places entailing the curtilage, as it were, of any licensed establishment. Unfortunately it's a 3rd degree felony too, so saving one's life by use of deadly force, and then subsequent conviction for violating the law, will result in permanant revocation of the person's right to carry a firearm. :/
It's okay though. Because, as we're told all the time, gun-free zones are effective and will keep us all safe! I'm sure Tiffany's just didn't have a big enough sign out front to let the perpetrators know....