Error when exporting model as SMD.
I get this error everytime I export a model as SMD.

Are you pressung the "export" button or the "save" button?
You'll want to press "save" to get the model out. The export button only handles textures.
That out of range error most likely has to do with a blank selection. So if you pull in a model without textures, and then press the texture export button, it might error like that
I’m pressing the save button.
the only other thing i can think of (without more provided details) is that perhaps a model is not selected. I'm pretty sure the highlight ought to be blue in the menu.
i know that when dealing with pokemon files, they have two models, a low and high poly. The low poly never saves for me. only the high poly. You may be able to get more assistance as well if you upload the file(s) having issues.