Nothing bad will happen if a dog eats raw potatoes.
Raw potatoes are safe for dogs to eat just like raw potatoes are safe for humans to eat.
Unless the potatoes have worms in them or some other parasite the dog should be just fine eating the raw potatoes.
The raw potatoes are actually beneficial to your dogs health and raw potatoes are likely even better for your dog than most dog food that you feed them.
Dogs can get worms from eating raw food but it's rare that they do.
Dogs are meant to eat raw food such as raw meat and it's perfectly fine for dogs to eat raw food such as raw hamburger, raw chicken, raw pork meat etc.
However it's best to not allow the dog to purposely eat the raw meat or other raw foods that could contain parasites as there is the slight potential for the dog to get worms from eating the raw meat and other raw food.
Some vets will also put dogs on a raw meat diet but when they do that they tell you to at least dip the raw meat into some boiling hot water for at least a few minutes.
The boiling hot water will kill off the parasites and worms that could be in the meat so that it does not potentially make your dog sick.
However my own dog as a kid used to eat old meat and old food without any issues and he lived to an old age.