Linux client failing to open links in firefox

Here's an obscure problem whose solution I worked out: if you run the Linux client without a desktop environment that sets the dbus session bus address, current versions of Electron (which the Discord client is based on) will set an environment variable that prevents libdbus from trying to be clever, which passes through xdg-open and tells firefox not to find your running browser. The real solution is to start your session bus from some specific point and set DBUS_SESSION_BUS_ADDRESS to the resulting address like desktops do it, but "DBUS_SESSION_BUS_ADDRESS=autolaunch:" in the environment where you start Discord will get the behavior you've come to expect from non-Electron programs. (This also applies to other Electron programs, such as VS code.)