Only mount xdg_runtime_dir when its env var is set

main.go

@@ -237,7 +237,17 @@ func Run(privileged bool, detach bool, mounts []string, command []string) error
 		waylandDisplay := os.Getenv("WAYLAND_DISPLAY")
 		if waylandDisplay != "" {
 			// let's be a little forceful with wayland use if it's available
-			dockerCommand = append(dockerCommand, "-e", "GDK_BACKEND=wayland")
+			dockerCommand = append(dockerCommand,
+				"-e", "GDK_BACKEND=wayland",
+				"-e", "WAYLAND_DISPLAY="+waylandDisplay,
+			)
+		}
+
+		if xdgRuntimeDir != "" {
+			dockerCommand = append(dockerCommand,
+				"--mount", "type=bind,source="+xdgRuntimeDir+",target="+xdgRuntimeDir,
+				"-e", "XDG_RUNTIME_DIR="+xdgRuntimeDir,
+			)
 		}
 
 		dockerCommand = append(
@@ -254,9 +264,6 @@ func Run(privileged bool, detach bool, mounts []string, command []string) error
 			"-e", "PULSE_SERVER=unix:/run/user/"+curUser.Uid+"/pulse/native",
 			"-e", "DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/"+curUser.Uid+"/bus",
 			"-v", "/tmp/.X11-unix:/tmp/.X11-unix",
-			"-e", "WAYLAND_DISPLAY="+waylandDisplay,
-			"-e", "XDG_RUNTIME_DIR="+xdgRuntimeDir,
-			"--mount", "type=bind,source="+xdgRuntimeDir+",target="+xdgRuntimeDir,
 			"-v", "/dev/snd:/dev/snd",
 			"-e", "DISPLAY="+os.Getenv("DISPLAY"),
 			"-e", "XAUTHORITY="+os.Getenv("XAUTHORITY"),