mate-screensaver crashed with SIGSEGV in matemenu_tree_item_ref()

[Norbert]

After long idle time mate-screensaver was not activated. Display backlight is dimmed, screen is not locked.

Lenovo SL500.

ProblemType: Crash
DistroRelease: Ubuntu 21.10
Package: mate-screensaver 1.26.0-0ubuntu1
ProcVersionSignature: Ubuntu 5.13.0-16.16-generic 5.13.13
Uname: Linux 5.13.0-16-generic x86_64
ApportVersion: 2.20.11-0ubuntu69
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: MATE
Date: Sun Sep 19 15:20:27 2021
ExecutablePath: /usr/bin/mate-screensaver
InstallationDate: Installed on 2021-09-19 (0 days ago)
InstallationMedia: Ubuntu-MATE 21.10 "Impish Indri" - Alpha amd64 (20210919)
ProcCmdline: /usr/bin/mate-screensaver --no-daemon
RebootRequiredPkgs: Error: path contained symlinks.
SegvAnalysis:
 Segfault happened at: 0x7f1acebe9b07 <matemenu_tree_item_ref+7>: lock addl $0x1,(%rdi)
 PC (0x7f1acebe9b07) ok
 source "$0x1" ok
 destination "(%rdi)" (0x00000000) not located in a known VMA region (needed writable region)!
SegvReason: writing NULL VMA
Signal: 11
SourcePackage: mate-screensaver
StacktraceTop:
 matemenu_tree_item_ref () from /lib/x86_64-linux-gnu/libmate-menu.so.2
 gs_theme_manager_lookup_theme_info ()
 ?? ()
 ?? ()
 g_closure_invoke () from /lib/x86_64-linux-gnu/libgobject-2.0.so.0
Title: mate-screensaver crashed with SIGSEGV in matemenu_tree_item_ref()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
separator:

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1943369, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.