It's only happened twice.
The first time was early into vaping, maybe only a few weeks in. Was in the car and all my eGo batteries pooped out on me. I thought they were both charged, but... Still 45 minutes away from home and I panicked - for all of 15 seconds. Once that was outta the way no problems, no freak out moment like with butts - no crazed panic with the sole thought of "Where's the closest Kwikee Mart dammit!" Just got home, found my other battery and life was good.
The other time was more recent. Had to get out the door and had 45 things distracting me and forgot my gear. I was more PO'd this time than panicked. I know I would survive the day, just wasn't all that happy about it.
Smoke instead? Not even a consideration. I'm one of the lucky many for whom everything about smoking got real disgusting, real fast, once I started vaping. (I'm trying really hard not to turn into one of those former smoker, anti smoking Nazis.)
Vaping - it's a good thing!