Debugging your system by reading logs or shell output
Debugging software
We going to use Pamac as an example, you need to find out the package name your application has, open Pamac and type your app name, were it says (/usr/bin/appname) is usually your executable.

Open a terminal and type your application name. Now on that terminal you can see if any errors output, not all applications output to the terminal, common errors that crash an application output (core dump, crash or assertion).

Using journalctl
Journalctl is part of systemd and logs any errors in your operating system, on journalctl the most important log to search is the error log, have a look at the bropages for more examples.
journalctl -p err
Using keywords to target a specific name search.
journalctl -p err | grep keyword

Checking Logs
Head to the directory (/var/log), not all application create logs in here but the ones that do you can open any file ending in (.log) and check their contents in plain text.
ls /var/log

If you on Xorg
Xorg is the default for any edition except for Gnome, then you can check (/home/.local/share/xorg/Xorg.0.log.) as Xorg logs errors that happens with any graphical application that runs.
Using Manjaro Log Helper can speed up this process by collecting all the system logs to one handy log and has some options to choose from.
pamac install manjaro-log-helper

- Also read:
- How to troubleshoot black screen on boot