Was thinking this unless it has snapped flush. Take some time to file a couple of flat sides so your mold grips get a good grip of the stud before you go chewing it up.
happens to us all worst case if it snaps inside the hole or flush to then there is only one or two options .
drill with a small drill bit down the center of the snapped bolt and then try to wind another smaller bolt down in to it tight then try see if you can wind it back out.
or drill bit the same size as the bolt and drill it all out being carfull not to go to deep or wide then once out make a new thread in the hole and use a slightly larger bolt .
I once did this on a side caseing and out of anger and rage shoulded bas****& and wacked the case with the socket wrench cracking the case . I was not please with my self and had a lot of not nice words said under my breath and some out load lol
Dads abit worried but I happens to him a lot being a mobile mechanic It has snapped flush, but I reckon just some left hand drill bits will do it Thanks guys