I haven't had this happen in a long time, but I had a new reason for a couple of close calls when I got my new bike a year ago. On my previous bike if I ever dropped the chain from the small chain ring to the inside I could almost always just soft-pedal and get it back onto the chainring within a couple of revolutions. I got used to dealing with it that way instead of stopping to adjust the FD limit screw like I should...

On my new bike if the chain drops to the inside it gets WEDGED in there, and if you continue to pedal you're going to seriously gouge up the frame. I can maybe make half a crank revolution before it stops. I've nearly fallen over on a steep upslope a couple of times from chain-drop incidents.

Moral of the story: adjust your FD limit screw...