Now this error was something that made me bang my head on the table. I had tried almost everything— looking up in google, stackover flow, adding my ssh key to the github account but nothing seem to work.
$ Permission denied (publickey). $ fatal: The remote end hung up unexpectedly
these are some of the solutions on stackoverflow that I had tried but none seemed to work.
and finally what did work was the most simplest solution of all
you just have to add these lines
$ ssh-add ~/.ssh/id_rsa