I have personal knowledge of 2 NDs that occurred with dry fire practice. I knew a detective, (sadly passed away a few years ago) who used to dry fire practice at his reflection in a full length mirror at the end of the hall in his home. He had been cleaning his service weapon (a S&W revolver) when he was interrupted by a phone call. He took the call and then went back to his weapon. His procedure was to always dry fire at that mirror after cleaning his weapon. So he walked back into the room, picked up his revolver, stepped into the hall and put a round through the mirror and the wall behind it. Fortunately there was no room behind the wall at the end of the hall. He told me the only thing he could think of was that when the phone rang, he loaded his revolver assuming the phone meant he was being called into work.
The other ND was a friend who routinely dry fired at his TV and somehow ended up with a loaded weapon and destroyed his TV.
I have a dedicated dry fire only target. When I dry fire in the house, I unload my weapon, leaving all of the ammunition in the other room. I hang up the dry fire target and I practice. When I finish, I take the target down, put it up and load my weapon. The only time I ever dry fire in the house is at that target. I don't trust myself not to get distracted and inadvertently point a loaded weapon at something I'm not willing to destroy. I've seen it happen to two very experienced people.