Can I use an electric smoker without wood chips as an oven to cook a ham?
I wouldn't recommend it, but that said your ham by definition has already been cured and all you are really doing is heating it.

Smokers are optimized for smoking meats at a lower temperature than a traditional oven or fire. They use a combination of smoke and water moisture to make great moist smoked meat. You could easily make your own ham by taking a pig's leg bone and "smoking" it with or without wood chips.

You should always use a smoker outside, and not indoors. Why can I have an indoor pizza/wood oven, but not a BBQ or smoker? (or can I...?)

Happy Easter!