Bug 420542

SUMMARY
When opening a file with .djvu files, it does not generate a thumbnail and constantly sends a notification that kdeinit5 has crashed. I have currently traced it down to line 72, but I have no idea what is the problem and why a fork is unavailable.

STEPS TO REPRODUCE
1. Make a folder with atleast 1 .djvu file
2. Wait for it to generate a thumbnail for Dolphin
3. 

OBSERVED RESULT
A notification is sent for a crash.

EXPECTED RESULT
A thumbnail for a .djvu file is shown.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: OpenSuse TUmbleweed 20200422, 
KDE Plasma Version: 5.18.4
KDE Frameworks Version: 5.69.0
Qt Version: 5.14.1

ADDITIONAL INFORMATION
Application: kdeinit5 (kdeinit5), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[KCrash Handler]
#6  0x00007f7e2aefd33e in __pthread_clockjoin_ex () from /lib64/libpthread.so.0
#7  0x00007f7e1f39c76f in thrd_join (res=0x0, thr=<optimized out>) at ../include/c11/threads_posix.h:329
#8  util_queue_kill_threads.part.0.constprop.0 (queue=0x55aa82a4be40, finish_locked=<optimized out>, keep_num_threads=0) at ../src/util/u_queue.c:496
#9  0x00007f7e1f7c18ca in util_queue_kill_threads (keep_num_threads=0, finish_locked=false, queue=0x55aa82a4be40) at ../src/util/u_queue.c:61
#10 atexit_handler () at ../src/util/u_queue.c:62
#11 0x00007f7e2b87d707 in __run_exit_handlers () from /lib64/libc.so.6
#12 0x00007f7e2b87d8bc in exit () from /lib64/libc.so.6
#13 0x00007f7e240f0a29 in DjVuCreator::create (this=this@entry=0x55aa828a81e0, path=..., width=width@entry=128, height=height@entry=128, img=...) at /usr/src/debug/kio-extras5-19.12.3-1.1.x86_64/thumbnail/djvucreator.cpp:77
#14 0x00007f7e28094dce in ThumbnailProtocol::get (this=0x7ffcb0029b40, url=...) at /usr/include/qt5/QtCore/qflags.h:118
#15 0x00007f7e28166c3e in KIO::SlaveBase::dispatch (this=0x7ffcb0029b40, command=67, data=...) at /usr/src/debug/kio-5.69.0-1.1.x86_64/src/core/slavebase.cpp:1198
#16 0x00007f7e2816de36 in KIO::SlaveBase::dispatchLoop (this=this@entry=0x7ffcb0029b40) at /usr/src/debug/kio-5.69.0-1.1.x86_64/src/core/slavebase.cpp:338
#17 0x00007f7e28096629 in kdemain (argc=<optimized out>, argv=0x55aa82834580) at /usr/src/debug/kio-extras5-19.12.3-1.1.x86_64/thumbnail/thumbnail.cpp:138
#18 0x000055aa81658bcb in launch (argc=4, _name=0x55aa828364b8 "/usr/lib64/qt5/plugins/kf5/kio/thumbnail.so", args=<optimized out>, cwd=<optimized out>, envc=0, envs=0x55aa8283655d "", reset_env=false, tty=0x0, avoid_loops=false, startup_id_str=0x55aa8165b175 "0") at /usr/src/debug/kinit-5.69.0-1.1.x86_64/src/kdeinit/kinit.cpp:708
#19 0x000055aa81659df8 in handle_launcher_request (sock=<optimized out>, who=<optimized out>) at /usr/src/debug/kinit-5.69.0-1.1.x86_64/src/kdeinit/kinit.cpp:1146
#20 0x000055aa8165a7d4 in handle_requests (waitForPid=0) at /usr/src/debug/kinit-5.69.0-1.1.x86_64/src/kdeinit/kinit.cpp:1339
#21 0x000055aa8165564d in main (argc=5, argv=<optimized out>) at /usr/src/debug/kinit-5.69.0-1.1.x86_64/src/kdeinit/kinit.cpp:1777
[Inferior 1 (process 10123) detached]