Comment 2 for bug 1836772

Before we debug anything here, one of your packages is broken, which might be relevant:

  libgl1-mesa-dri 18.0.0~rc5-1ubuntu1

It should be version 19. To fix this please run:

  sudo apt update
  sudo apt full-upgrade

If that doesn't fix it then download and install the missing package:

  https://launchpad.net/ubuntu/+archive/primary/+files/libgl1-mesa-dri_19.0.2-1ubuntu1.1~18.04.1_amd64.deb

and reboot.