dwalk segfaults when attempting to output text on many files

as in subject, here's an output run:

$ dwalk -i mhm -s -size -to sorted.out
[2026-05-12T17:00:49] Reading from input file: mhm
[2026-05-12T17:00:49] Read 29864 files in 0.074 seconds (405157.059 files/sec)
[2026-05-12T17:00:49] Sorted 29864 items in 0.023 seconds (1271661.823 items/sec)
[2026-05-12T17:00:49] Items: 29864
[2026-05-12T17:00:49] Directories: 2589
[2026-05-12T17:00:49] Files: 27221
[2026-05-12T17:00:49] Links: 54
[2026-05-12T17:00:49] Data: 5.241 GiB (201.899 KiB per file)
[2026-05-12T17:00:49] Writing to output file: sorted.out
[muscadine-node-1:2797762:0:2797762] Caught signal 11 (Segmentation fault: address not mapped to object at address 0x8)
==== backtrace (tid:2797762) ====
0 0x000000000006141c ucs_callbackq_cleanup() ???:0
1 0x00000000000615da ucs_callbackq_cleanup() ???:0
2 0x000000000003e6f0 __GI___sigaction() :0
3 0x00000000000cf2b7 __strftime_internal() ???:0
4 0x00000000000d144c __GI___strftime_l() :0
5 0x000000000002206f print_file_text() mfu_flist_io.c:0
6 0x0000000000025abf mfu_flist_write_text() ???:0
7 0x0000000000402cdf main() ???:0
8 0x0000000000029590 __libc_start_call_main() ???:0
9 0x0000000000029640 __libc_start_main_alias_2() :0
10 0x0000000000403425 _start() ???:0

[1] 2797762 segmentation fault (core dumped) dwalk -i mhm -s -size -to sorted.out

Please ask me if you need more information.

Reproduce the failure with the reported dwalk command and inspect mfu_flist_io.c, especially print_file_text() and mfu_flist_write_text() in the backtrace. Trace the strftime-related output path for large file lists, then verify that the command completes without a segmentation fault and writes sorted.out.