Well that sucks. But…clean breaks. You can drill those out and extract them. Clean the threads and put in new bolts. Center punch then start with the smallest drill bit in the set. Go slow and steady light pressure. Drilling oil is best but you can use about any oil to help keep the bit from getting hot. I use penetrating oil as that’s usually what’s handy. Drill all the way through. Then go step by step in drill bits until you can fit an extractor. Usually the heat of drill will help break out the rust. Worst case scenario, you drill out the hole, ruin the threads, find a bolt, nut, and lock washer and install through that hole.