No bulb in it at all?
Hopefully the last owner removed it so (s)he knew what to buy, then never got round to completing the job.
However, there may be a darker reason (forgive the pun) there was no bulb, such as it staying on when it shouldnt or similar. At least in this case, it will be obvious the light is on.
I once discovered a missing boot light bulb (not on a hatch back) and felt really pleased with myself when I replaced it. Shortly after, the car started to suffer from random flat batteries. I spent ages trying to cure this (including a new battery) until one day I remembered the boot light bulb. It was randomly not switching off, and when the car was left for more than a few days..... The fault was actualy an intermitent switch, but the last owner had "curred" it by removing the bulb.