The only problems with wood chips is sometimes they get jammed in the mouth and need to be removed (stuck in bleeding and such) and if there is not a chip or two but a lot ingested with a small snake it can lead to impacted bowels. I have a one eyed snake with horrible aim she managed to get a mouth full (FULL) of substrate and subsequent digestion issues that took laxatives be administered.

Typically a normal snake will have no issues with substrate ingestion it is just the stuck in the mouth that can occur to be concerned with. You could use a shield placed well before feeding can solve this. I used to use a think (1 mm) plastic sheet about as big as my hand that I fed over it helped a fair bit. The only substrate that ingestion is a HUGE deal is paper towel. I would not suggest paper towel with anything but a hatchling. (goggle image search paper towel ingestion snakes you'll see what I mean be warned it is unpleasant) There are many alternatives, so I see no reason to risk the life/health of an animal to use paper towel (no matter how remote) . Personally I use coco husk and have had no issues it soft and breaks down easily (wood breaks down too but too much overwhelms the system)