Why does my motorcycle cut off at an intersection?

I recently bought a 93 honda nighthawk cb250 and sometimes when I'm coming to a stop and I'm downshifting and I get to first gear and make the stop the engine kinda cuts out i don't know what I'm doing wrong if anything, is it the choke? Am I not supposed to downshift before stopping? This is my first bike and I need some help.

The choke should only be used to aid starting on cold mornings otherwise leave the engine unchoked.

If you are not holding the clutch in then the engine will stall. But it is not possible from your description to guess what you are doing wrong. A professional training course is always worth the time and effort.