Assert failure in LinuxPort cleanup

[pstavirs]

Sometimes when hitting Ctrl+C on Drone in Linux, the following abort crash is seen -

[::ffff:127.0.0.1:37556] ---->                                                                  
^CIn ~LinuxPort                                                                                                                                                             
[::ffff:127.0.0.1:37556] ASSERT failure in QList<T>::operator[]: "index out of range", file /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h, line 549
Aborted        

The backtrace for the same is as follows -

(gdb) bt
#0  0x0000555555576e10 in qt_assert_x(char const*, char const*, char const*, int)@plt ()
#1  0x00005555555af7b5 in QList<QReadWriteLock*>::operator[] (this=0x5555559426a0, i=0)
    at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:549
#2  0x00005555555a9e57 in MyService::getStats (this=0x555555942680,
    request=0x7fff54056e40, response=0x7fff54013e10, done=0x7fff5405aee0)
    at myservice.cpp:620
#3  0x000055555562345c in OstProto::OstService::CallMethod (this=0x555555942690,
    method=0x7fff54025cb8, controller=0x7fff540557e0, request=0x7fff54056e40,
    response=0x7fff54013e10, done=0x7fff5405aee0) at protocol.pb.cc:17235
#4  0x000055555568b27e in RpcConnection::on_clientSock_dataAvail (this=0x55555599b900)
    at rpcconn.cpp:388
#5  0x000055555568c664 in RpcConnection::qt_static_metacall (_o=0x55555599b900,
    _c=QMetaObject::InvokeMetaMethod, _id=3, _a=0x7fffe8cdbad0) at moc_rpcconn.cpp:102
#6  0x00007ffff61bb555 in QMetaObject::activate(QObject*, int, int, void**) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007ffff6bc0843 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Network.so.5
#8  0x00007ffff6bc08f4 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Network.so.5
#9  0x00007ffff6bd47a1 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Network.so.5
#10 0x00007ffff618c8c1 in QCoreApplication::notifyInternal2(QObject*, QEvent*) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007ffff61e64ed in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#12 0x00007ffff407a417 in g_main_context_dispatch ()
   from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#13 0x00007ffff407a650 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#14 0x00007ffff407a6dc in g_main_context_iteration ()
   from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#15 0x00007ffff61e58ab in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#16 0x00007ffff618a90a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#17 0x00007ffff5fa923a in QThread::exec() ()
   from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#18 0x00007ffff5fae17d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007ffff5cea6db in start_thread (arg=0x7fffe8cdc700) at pthread_create.c:463
#20 0x00007ffff50d4a3f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
(gdb) f 1
#1  0x00005555555af7b5 in QList<QReadWriteLock*>::operator[] (this=0x5555559426a0, i=0)
    at /usr/include/x86_64-linux-gnu/qt5/QtCore/qlist.h:549
549     { Q_ASSERT_X(i >= 0 && i < p.size(), "QList<T>::operator[]", "index out of range");
(gdb) up
#2  0x00005555555a9e57 in MyService::getStats (this=0x555555942680,
    request=0x7fff54056e40, response=0x7fff54013e10, done=0x7fff5405aee0)
    at myservice.cpp:620
620             portLock[portId]->lockForRead();
(gdb) print portId
$1 = 0