If someone was wearing one of Voldemort’s horcruxes (say the locket for example) and he tried to use the killing curse on them, but the spell hit the locket not them, what would happen? Would they die? Would the horcrux break? Would the spell rebound?

Because I know the killing curse doesn’t work on horcruxes, however what if it was cast by their original master? And would the witch/wizard die if the spell hit it and not them?