I have this happen to fairly often me due to having a few extra plants that I don't mind pushing hard because they are kind of like the the runts of the group that I play with a little more. I've split stems straight down the middle during veg and I've even had it happened in the middle of flower a couple times. All I do is put a little bit of cloning / rooting hormone on the cut / break and wrap it up with a little bit of electrical tape to hold it together for support. Most of the time they don't even wilt or act like anything has ever happened! but it can, so like Mr. Shrubber was mentioning I would just keep an eye on it. But usually as long as the plant is healthy they can take a little bit of a beating. I wouldn't ever intentionally do it but things like that do happen in this hobby. All in all, they are pretty tough and resilient plants, they just want to grow. It kind of reminds me of people putting a nail through the main stalk lol