Dig into the drywall above the door, load bearing would be indicated with another beem there.
You can remove a little ceiling to make sure you don't have a join in a floor joist landing on it.
Just so you know, a normal corner has 2 2x4 nail in an L shape with another stud for drywall back on the other wall and a normal door has 2 2x4 nailed together on each side of the door.
When you have a corner and a door in the same place, there is a problem because you want to fill an area of 3 1/2" x 3 1/2" and 2 2x4 only give you 3" x 3 1/2". The normal is to fill the gap with a peice of plywood or whatever is laying around. If you are lucky enough to have a 3 1/2 x 3 1/2 post, it goes in. So it likely dosn't mean anything.
I hope that all makes sence and welcome to the site and double checking when your not sure is a great idea.