Ok,
Can you share what you did trying to fix your issue (?), because on my side, i don't have that problem. First i did check my gem version gem -v, (2.2.2) then i put all up to date. And i can't get that error again.
Some basic stuff i did to try make msf crash

:
sudo -i
apt update
apt upgrade
apt-get dist-upgrade
msfupdate
Next to do is gems updating, but skip this step, will take awhile and i don't know how other tools will act after that, run msfconsole before.
gem update
Try:
msfconsole
If you have problems even after this, update gems (on your own risk). I did even step with gems updates on my side, and again i get what i want:

All goes well.