What would be the hazard of raising flaps on the ground? I was reading ASRS report when I found something I don’t understand. What would be the hazard of raising flaps on the ground? What bad thing can happen?

However, with all the activity around the aircraft, including refueling, it was not safe to raise the flaps. I elected…not to raise the flaps until the area cleared.

https://asrs.arc.nasa.gov/publications/callback/cb_482.html
Without knowing what type of aircraft was involved in this incident, it is hard to tell. But, in general, a moving flap would provide a pinch point for any personnel in the area. Considering the article mentions that the hydraulics were in the on position, there would be a possibility of crushing a body part of maintenance personnel.