Emacs extension magit-gh-pulls not working

[良ϖ]

Hi, not sure it's off-topic, please tell where to head to if it is.

I've installed version 20161020.249 of this package through melpa and
added the required hooks. At first glance PR list is retrieved so it
looks good.

However when I try to fetch a PR I get this error message:
eq: Wrong type argument: lisp, unfetched-pull

When I put the pointer on a PR and press enter, I get:
eq: Wrong type argument: listp, pull

I'm using
 - GNU Emacs 26.0.50 (build 1, x86_64-apple-darwin16.3.0, NS
appkit-1504.76 Version 10.12.2 (Build 16C67)) of 2017-03-03
 - magit-gh-pulls version: 20161020.249

Did I miss something? would this package be messing with an unexpected
GitHub API change? how could I debug it and see what happen inside?
(I'm newbie in Emacs debugging but it's OK to learn)

piotr