greetd fails to start with panic from wlgreet

[Jeff Abrahamson]

I've tried starting greetd using the config installed by default and the config as modified by the docs. I've tried to start it by saying this at the console before starting sway:

$ sudo systemctl start greetd

/etc/greetd/config.toml says

> command = "sway --config /etc/greetd/sway-config"

/etc/greetd/sway-config says (one of)

> exec "/usr/sbin/wlgreet; swaymsg exit"
> exec "/usr/sbin/wlgreet --command sway; swaymsg exit"

On starting greetd, the screen flashes this error (the same in both cases):

thread 'main' panicked at 'internal error: entered unreachable code', src/app.rs:473:48
...RUST_BACKTRACE advice...
[wayland-client error] A handler for wl_surface panicked.
Aborted (core dumped)
00:00:00.090 [common/ipc-client.c:87] Unable to receive IPC response

I tried setting RUST_BACKTRACE, but didn't understand much and didn't see how to capture the output to include here.

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: wlgreet 0.4.1-3
ProcVersionSignature: Ubuntu 6.8.0-41.41-generic 6.8.12
Uname: Linux 6.8.0-41-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.1
Architecture: amd64
CasperMD5CheckResult: pass
Date: Thu Sep 5 20:58:00 2024
InstallationDate: Installed on 2023-12-02 (278 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Release amd64 (20220419)
SourcePackage: wlgreet
UpgradeStatus: Upgraded to noble on 2024-08-30 (6 days ago)
mtime.conffile..etc.greetd.sway-config: 2024-09-05T20:45:53.374205
mtime.conffile..etc.init.d.apport: 2024-07-22T16:59:07