Um. I have reupholstered couches, chairs and cars, the table was a breeze, it's flat and square, no weird curves or trim. Depending on how it's made with the warmer, it's no more complex than wrapping a box in
gift wrap paper, and stapling it to the edge bars. If there are cut outs in the upholstery for the warmer, it might add a bit of weirdness, not much.
Pro tip, if you do it, that covering is stapled seriously, cut the fabric away from the
staple line, leave the staples and fabric scrap in place, staple above or below that line. That'll be a not fun mess to pull all of the staples, and it's not visible, so it doesn't matter.
:D