How to make systemd not hang (unresponsive system), but provide emergency shell?

I am not very familiar with systemd. The answer I seek with this question is: How is it possible to make **systemd** react to problems with "dropping the user into an emergency shell of sorts", instead of simply having an unresponsive system? Example for being explicit: Case of an install of arch linux on a thinkpad, it seems that there is some miscofiguration of the x-org-server, or wayland, or maybe systemd, or lightdm, which instead of producing a error message leaves the user hung up. This means that the user sees the service/startup messages being output to tty1 come to stop, without any having any error message produced (if there is one the glorious **systemd-journald** ate it??) and no key combination whatsoever can even produced a root shell to enable the user to check for the error and correct it. Consequenlty the answer how to configure systemd to drop into a emergency shell to avoid a hung up system at any error, on the way to a **graphical.target** How such a hung up situation might be like is done for instance in this U&L question "arch-linux-hang-on-reached-target-graphical-interface "