N.B.: I couldn't submit this bug through drkonqi, as the indexing agent was missing some information necessary to link it to bugzilla

SOFTWARE/OS VERSIONS
Akonadi: 5.9.3 (shouldn't this be added to the options in the bug report dropdown?) 
(available in About System)
KDE Plasma Version: 5.14.5
KDE Frameworks Version: 5.54.0
Qt Version: 5.11.3

ADDITIONAL INFORMATION

Application: akonadi_indexing_agent (akonadi_indexing_agent), signal: Aborted
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f249f8ef300 (LWP 10968))]

Thread 4 (Thread 0x7f247f17c700 (LWP 11004)):
[KCrash Handler]
#6  0x00007f249b25f83b in raise () from /lib64/libc.so.6
#7  0x00007f249b261081 in abort () from /lib64/libc.so.6
#8  0x00007f249b8c3065 in __gnu_cxx::__verbose_terminate_handler() () from /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/libstdc++.so.6
#9  0x00007f249b8c0c26 in ?? () from /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/libstdc++.so.6
#10 0x00007f249b8c0c71 in std::terminate() () from /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.0/libstdc++.so.6
#11 0x00007f249bc91e56 in qTerminate () at global/qglobal.cpp:3193
#12 0x00007f249bcb8b57 in QThreadPrivate::start (arg=0x55f19dd644e0) at thread/qthread_unix.cpp:379
#13 0x00007f249821296a in start_thread () from /lib64/libpthread.so.0
#14 0x00007f249b32d92f in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7f247f97d700 (LWP 11003)):
#0  0x00007f249b31d460 in read () from /lib64/libc.so.6
#1  0x00007f249641eb70 in ?? () from /usr/lib64/libglib-2.0.so.0
#2  0x00007f24963d9ba7 in g_main_context_check () from /usr/lib64/libglib-2.0.so.0
#3  0x00007f24963da060 in ?? () from /usr/lib64/libglib-2.0.so.0
#4  0x00007f24963da1cc in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#5  0x00007f249be9ef5b in QEventDispatcherGlib::processEvents (this=0x7f2478000b20, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#6  0x00007f249be4affa in QEventLoop::exec (this=this@entry=0x7f247f97ccf0, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#7  0x00007f249bcaef5a in QThread::exec (this=<optimized out>) at thread/qthread.cpp:525
#8  0x00007f249c2d7de5 in ?? () from /usr/lib64/libQt5DBus.so.5
#9  0x00007f249bcb89af in QThreadPrivate::start (arg=0x7f249c54fd60) at thread/qthread_unix.cpp:367
#10 0x00007f249821296a in start_thread () from /lib64/libpthread.so.0
#11 0x00007f249b32d92f in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f248a0be700 (LWP 10987)):
#0  0x00007f249b321d63 in poll () from /lib64/libc.so.6
#1  0x00007f2492bc87f7 in ?? () from /usr/lib64/libxcb.so.1
#2  0x00007f2492bca42a in xcb_wait_for_event () from /usr/lib64/libxcb.so.1
#3  0x00007f248c631779 in QXcbEventReader::run (this=0x55f19dcff5d0) at qxcbconnection.cpp:1391
#4  0x00007f249bcb89af in QThreadPrivate::start (arg=0x55f19dcff5d0) at thread/qthread_unix.cpp:367
#5  0x00007f249821296a in start_thread () from /lib64/libpthread.so.0
#6  0x00007f249b32d92f in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f249f8ef300 (LWP 10968)):
#0  0x00007f249b321d63 in poll () from /lib64/libc.so.6
#1  0x00007f24963da0b9 in ?? () from /usr/lib64/libglib-2.0.so.0
#2  0x00007f24963da1cc in g_main_context_iteration () from /usr/lib64/libglib-2.0.so.0
#3  0x00007f249be9ef5b in QEventDispatcherGlib::processEvents (this=0x55f19dd4e6f0, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#4  0x00007f248c6ba5d1 in QPAEventDispatcherGlib::processEvents (this=0x55f19dd4e6f0, flags=...) at qeventdispatcher_glib.cpp:69
#5  0x00007f249be4affa in QEventLoop::exec (this=this@entry=0x7ffed6c3ae40, flags=..., flags@entry=...) at kernel/qeventloop.cpp:214
#6  0x00007f249be539e0 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1335
#7  0x00007f249c64703c in QGuiApplication::exec () at kernel/qguiapplication.cpp:1762
#8  0x00007f249d023ce5 in QApplication::exec () at kernel/qapplication.cpp:2900
#9  0x00007f249ed76029 in Akonadi::AgentBase::init (r=0x55f19dd474b0) at /var/tmp/portage/kde-apps/akonadi-18.08.3-r1/work/akonadi-18.08.3/src/agentbase/agentbase.cpp:973
#10 0x000055f19ce8b9c3 in ?? ()
#11 0x00007f249b24ab87 in __libc_start_main () from /lib64/libc.so.6
#12 0x000055f19ce8805a in _start ()