I also applied 187DE AFTER 457 finished so we have two thing first nomination refuse then some time Case officers allow you to withdraw your visa application then you 28 days to application any visa but then you will get bridging visa after new visa application onshore.
second, if nominations and Visa both refuse then if do not hold any visa the section 48 will apply. You cannot apply onshore any visa. If any substantive visa live when your file get refused then you can apply any visa onshore. So just relax and if think you need to apply 457 / 482 then do it now while you are on bridging visa A .
if apply 482 new 457 then you will get bridging visa E. Ok