After clicking on close button, SIGSEGV is encountered. 

Reproducible: Always

Steps to Reproduce:
1. Open Dolphin
2. Close window using close button on title bar



Application: dolphin (dolphin), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fc19a97b800 (LWP 22677))]

Thread 2 (Thread 0x7fc18155d700 (LWP 22679)):
#0  0x00007fc18d7ae044 in g_mutex_unlock () from /usr/lib/libglib-2.0.so.0
#1  0x00007fc18d769500 in g_main_context_prepare () from /usr/lib/libglib-2.0.so.0
#2  0x00007fc18d769efb in ?? () from /usr/lib/libglib-2.0.so.0
#3  0x00007fc18d76a0ec in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#4  0x00007fc19448c59b in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#5  0x00007fc1944360da in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
#6  0x00007fc1942590f3 in QThread::exec() () from /usr/lib/libQt5Core.so.5
#7  0x00007fc19489de75 in ?? () from /usr/lib/libQt5DBus.so.5
#8  0x00007fc19425dd78 in ?? () from /usr/lib/libQt5Core.so.5
#9  0x00007fc18f8bb484 in start_thread () from /usr/lib/libpthread.so.0
#10 0x00007fc19a30e6dd in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7fc19a97b800 (LWP 22677)):
[KCrash Handler]
#5  0x00007fc19781d994 in std::__atomic_base<int>::load (__m=std::memory_order_relaxed, this=0x7fc17bb6e8e0) at /usr/include/c++/6.1.1/bits/atomic_base.h:396
#6  QAtomicOps<int>::load<int> (_q_value=...) at /usr/include/qt/QtCore/qatomic_cxx11.h:103
#7  QBasicAtomicInteger<int>::load (this=0x7fc17bb6e8e0) at /usr/include/qt/QtCore/qbasicatomic.h:99
#8  QtPrivate::RefCount::deref (this=0x7fc17bb6e8e0) at /usr/include/qt/QtCore/qrefcount.h:66
#9  QString::~QString (this=0x249ccc0, __in_chrg=<optimized out>) at /usr/include/qt/QtCore/qstring.h:1075
#10 QHashNode<QString, QHashDummyValue>::~QHashNode (this=<optimized out>, __in_chrg=<optimized out>) at /usr/include/qt/QtCore/qhash.h:164
#11 QHash<QString, QHashDummyValue>::deleteNode2 (node=0x249ccb0) at /usr/include/qt/QtCore/qhash.h:533
#12 0x00007fc1942bc109 in QHashData::free_helper(void (*)(QHashData::Node*)) () from /usr/lib/libQt5Core.so.5
#13 0x00007fc197819dac in QHash<QString, QHashDummyValue>::freeData (this=0x1fc9020, x=<optimized out>) at /usr/include/qt/QtCore/qhash.h:573
#14 QHash<QString, QHashDummyValue>::~QHash (this=0x1fc9020, __in_chrg=<optimized out>) at /usr/include/qt/QtCore/qhash.h:252
#15 QSet<QString>::~QSet (this=0x1fc9020, __in_chrg=<optimized out>) at /usr/include/qt/QtCore/qset.h:54
#16 KIconLoaderPrivate::~KIconLoaderPrivate (this=0x1fc8fb0, __in_chrg=<optimized out>) at /home/r4pt0r/Downloads/packages/kiconthemes/repos/extra-x86_64/src/kiconthemes-5.23.0/src/kiconloader.cpp:188
#17 KIconLoader::~KIconLoader (this=0x7fc197a31f20 <(anonymous namespace)::Q_QGS_globalIconLoader::innerFunction()::holder>, __in_chrg=<optimized out>) at /home/r4pt0r/Downloads/packages/kiconthemes/repos/extra-x86_64/src/kiconthemes-5.23.0/src/kiconloader.cpp:610
#18 0x00007fc197819e29 in (anonymous namespace)::Q_QGS_globalIconLoader::Holder::~Holder (this=<optimized out>, __in_chrg=<optimized out>) at /home/r4pt0r/Downloads/packages/kiconthemes/repos/extra-x86_64/src/kiconthemes-5.23.0/src/kiconloader.cpp:1701
#19 0x00007fc19a25cbe8 in __run_exit_handlers () from /usr/lib/libc.so.6
#20 0x00007fc19a25cc35 in exit () from /usr/lib/libc.so.6
#21 0x00007fc19a247748 in __libc_start_main () from /usr/lib/libc.so.6
#22 0x0000000000400719 in _start ()

This may be related to icon settings in plasma, since I am using old oxygen set, preinstalled with my distro and as far as I understand the problem is with something about handling icons.

I am using newest packages available in Arch Linux, that is kiconthemes 5.23.0, Dolphin 16.04.2 and qt5-base 5.7.0.

I am not sure if I used right category when filling bug report (don't know if it is view-engine related), so sorry if that is the case.