Inbound TCP/IP connection failed: 'function' object has no attribute 'peer_subscribe'

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I have two nodes, one publishes a topic ( https://github.com/pitosalas/easy_fil... ) that the other one ( https://github.com/pitosalas/easy_fil... ) subscribes to. What happens is if I run the publsher by itself, all is well. But if I do a rostopic echo on the relevant topic then the publisher starts throwing that exception.

Three notes:

1. I've been debugging for a while, with control-c and kill commands to try and cleanup. I could be in some kind of bad state. But then my question is: how do I tell and how do I get out of the bad state? What do I reboot, my development computer, my robot, my roscore computer, all of them? And how do I avoid getting into this state.
2. Minor: is the / before the topic name (when used in the publish or subscribe call) required, optional or sometimes yes and sometimes no?
3. I am working in python,