A compelling argument could be made that North Korea does not, in fact, have a national economy due to its extreme plight. It has been in a state of complete and total economic collapse for nearly a decade, and complete economic collapse is something that has only happened a few times in recorded history, such as what happened to Nazi Germany in early 1945 as the result of carpet bombing and the invading armies of three major world powers. Even with all those war stresses, it wasn't until 1945 that the economy was considered to be in total collapse. North Korea has been there for almost 10 years now.

I would mention Somalia, but I think to have an economy you generally need to have a country to begin with.

As for war communism, well, that was to be expected. It's a wonder the Bolsheviks survived through to Stalin. If their enemies were even SLIGHTLY more coordinated, they would have fallen (and saved the world a LOT of misery).