budgie-wm core dump since update to mutter 48

Description:

After updating to mutter 48, budgie-wm coredump immediately after it starts:

Journalctl logs

mars 23 19:17:47 arch budgie-wm[1245]: Running Mutter(Budgie) (using mutter 0.9.4) as a X11 window and compositing manager
mars 23 19:17:47 arch budgie-wm[1245]: g_variant_get_string: assertion 'value != NULL' failed
mars 23 19:17:47 arch budgie-wm[1245]: The mapping function given to g_settings_get_mapped() for key 'overlay-key' in schema 'org.gnome.mutter' returned FALSE when given a NULL value.
mars 23 19:17:47 arch kernel: traps: budgie-wm[1245] trap int3 ip:707412c51248 sp:7ffd1ac42ac0 error:0 in libglib-2.0.so.0.8400.0[63248,707412c0c000+a7000]
mars 23 19:17:47 arch systemd-coredump[1256]: Process 1245 (budgie-wm) of user 1000 terminated abnormally with signal 5/TRAP, processing...
mars 23 19:17:47 arch systemd[1]: Started Process Core Dump (PID 1256/UID 0).
mars 23 19:17:48 arch systemd-coredump[1257]: Process 1245 (budgie-wm) of user 1000 dumped core.
mars 23 19:17:48 arch systemd[1]: systemd-coredump@1-1256-0.service: Deactivated successfully.
mars 23 19:17:48 arch systemd[1]: systemd-coredump@1-1256-0.service: Consumed 350ms CPU time, 78M memory peak.
mars 23 19:17:48 arch budgie-session-binary[973]: WARNING: Application 'org.buddiesofbudgie.BudgieWm.desktop' killed by signal 5
mars 23 19:17:48 arch budgie-session[973]: budgie-session-binary[973]: WARNING: Application 'org.buddiesofbudgie.BudgieWm.desktop' killed by signal 5
mars 23 19:17:48 arch budgie-session[973]: budgie-session-binary[973]: WARNING: App 'org.buddiesofbudgie.BudgieWm.desktop' respawning too quickly
mars 23 19:17:48 arch budgie-session-binary[973]: Unrecoverable failure in required component org.buddiesofbudgie.BudgieWm.desktop
mars 23 19:17:48 arch budgie-session-binary[973]: WARNING: App 'org.buddiesofbudgie.BudgieWm.desktop' respawning too quickly

GDB backtrace

(gdb) bt
#0  g_log_structured_array (log_level=log_level@entry=G_LOG_LEVEL_ERROR, fields=fields@entry=0x7ffd1ac42b10, n_fields=4)
    at ../glib/glib/gmessages.c:431
#1  0x0000707412c51547 in g_log_default_handler
    (log_domain=log_domain@entry=0x707412f097cb "GLib-GIO", log_level=log_level@entry=6, message=message@entry=0x642badca9970 "The mapping function given to g_settings_get_mapped() for key 'overlay-key' in schema 'org.gnome.mutter' returned FALSE when given a NULL value.", unused_data=unused_data@entry=0x0) at ../glib/glib/gmessages.c:3434
#2  0x0000707412c517cc in g_logv
    (log_domain=0x707412f097cb "GLib-GIO", log_level=G_LOG_LEVEL_ERROR, format=<optimized out>, args=args@entry=0x7ffd1ac42c60)
    at ../glib/glib/gmessages.c:1260
#3  0x0000707412c51b54 in g_log
    (log_domain=log_domain@entry=0x707412f097cb "GLib-GIO", log_level=log_level@entry=G_LOG_LEVEL_ERROR, format=format@entry=0x707412f21fb0 "The mapping function given to g_settings_get_mapped() for key '%s' in schema '%s' returned FALSE when given a NULL value.") at ../glib/glib/gmessages.c:1329
#4  0x0000707412e97403 in g_settings_get_mapped
    (settings=0x642badc9db00, key=key@entry=0x707412b8b092 "overlay-key", mapping=mapping@entry=0x707412aad0e0 <overlay_key_handler>, user_data=user_data@entry=0x0) at ../glib/gio/gsettings.c:1820
#5  0x0000707412aa6a87 in handle_preference_init_string () at ../magpie-0.9.4/src/core/prefs.c:583
#6  meta_prefs_init () at ../magpie-0.9.4/src/core/prefs.c:1042
#7  meta_context_start (context=context@entry=0x642bad801070, error=error@entry=0x7ffd1ac42ef0) at ../magpie-0.9.4/src/core/meta-context.c:425
#8  0x0000642b838a32a4 in _vala_main (args=<optimized out>, args_length1=<optimized out>) at src/wm/budgie-wm.p/main.c:164
#9  main (argc=<optimized out>, argv=<optimized out>) at src/wm/budgie-wm.p/main.c:206

Downgrading mutter to 47.6-1 resolves the issue.

See also this issue on arch forums: https://bbs.archlinux.org/viewtopic.php?id=304403

This issue was already reported to Ubuntu maintainers (which experienced the same crash) who made a patch to budgie-desktop that was merged upstream. However, this patch has not been released in any version yet.

I know Arch's philosophy is to avoid to patch upstream code, but since budgie-desktop completely crashes currently, is it possible to exceptionally backport this patch until the upstream releases a new version that includes it?

Steps to reproduce:

1. Install budgie-desktop (or update a system that already runs budgie-desktop so that it now has mutter 48 installed)
2. budgie-vm crashes immediately after being started.

added priority3-normal severity4-low statusunconfirmed labels

assigned to @freswa, @toolybird, and @gromit

changed the description

Just to note 46c83b1 Resolve vala 0.56.18 compact class inheritance removal - closes #679 will be needed to allow the package to build with vala 0.56.18. In addition to c24091b Add override for overlay-key to prevent crash with mutter-common v48-rc (#683) for this issue.

added backport-request label

added scoperegression severity2-high statusconfirmed labels and removed severity4-low statusunconfirmed labels

assigned to @serebit and unassigned @freswa, @toolybird, and @gromit

closed with commit cf1c15fd