Sorry to post again, but I believe I found another bug. I just spied a country that had 0 population left, thus that country should be dead, which it was(unable to attack it, just able to spy it).

Another possible bug is I am still DW'ed on the country. I am pretty sure that when a country dies the decloration of war is suppose to cancel it self.

Just wanted to let your game fixers know.
Thanks, me.

Spy ops on dead countries is not a bug

DW on dead countries doesn't go away automatically, but when they die you can declare peace earlier than usual

you can try steal techs from dead country if it has low spal.