Hi, Welcome!
Looks like that is your issue. mini_racer segfaults.
This mini_racer-0.17.0.pre12 version has been introduced at DEV: update mini_racer by SamSaffron · Pull Request #30656 · discourse/discourse · GitHub.
There were several attempts to fix mini_racer previously, from 3.4.0.beta2 to beta4, so I would wait for team feedback before upgrading.