So finally the error is gone.
I added this environment variable to my Openshift proyect:
LD_PRELOAD = '/opt/app/node_modules/sharp/vendor/lib/libz.so'
This is the url to sharp inside my node_modules.
When I opened the terminal I get and error saying that it can't be preloaded but after installing all dependencies the error is gone, and I could upload images!!!
Thank you very much @PitaJ !!!!
Hmm... there's always /nickserv identify, but I have absolutely zero idea how that even works.
What if you made your own bot that listened for private messages from users, and verified them? So all I had to do was /yourbot julian hunter2?
Then your bot would probably communicate with a companion plugin on our end to verify users by username/password... There's a possibly MITM issue present if you don't use HTTPS though... less so if everything is on one machine and you're communicating via localhost connections...