Mac OS App crashes on exit in QCompleter if close is triggered via taskbar

Whenever I close my application via CMD+Q (which calls QApplication::closeAllWindows()) the application shuts down as expected. But closing the application via the task bar (right mouse click and Close) the application crashes inside any QCompleter (I don't even construct the completers myself, they are installed by QComboBox itself).
The crash happens here:

void QCompletionModel::filter(const QStringList& parts)
{
    Q_D(QCompletionModel);
    beginResetModel();
    engine->filter(parts);
    endResetModel();
    if (d->model->canFetchMore(engine->curParent))
        d->model->fetchMore(engine->curParent);
}

I could not construct a simple example, so there might be some other component required for the behaviour to occur. My application is fairly large, so a lot of code needs to be cleaned on shutdown.

That's the call stack:
1 QCompletionModel::filter(QList<QString> const&) qcompleter.cpp 391 0x1022ba825
2 void doActivate<false>(QObject *, int, void * *) qobject.cpp 4150 0x1033d02b1
3 QMetaObject::activate(QObject *, QMetaObject const *, int, void * *) qobject.cpp 4198 0x1033c69bb
4 void QMetaObject::activate<void, QObject *>(QObject *, QMetaObject const *, int, void *, QObject * const&) qobjectdefs.h 306 0x1033c699d
5 QObject::destroyed(QObject *) moc_qobject.cpp 186 0x1033c698d
6 QObject::~QObject() qobject.cpp 1042 0x1033c698d
7 QStandardItemModel::~QStandardItemModel() qstandarditemmodel.cpp 2242 0x1018d7eef
8 QStandardItemModel::~QStandardItemModel() qstandarditemmodel.cpp 2236 0x1018d7e31
9 QStandardItemModel::~QStandardItemModel() qstandarditemmodel.cpp 2236 0x1018d7e31
10 QObjectPrivate::deleteChildren() qobject.cpp 2223 0x1033c7131
11 QWidget::~QWidget() qwidget.cpp 1563 0x101ecbec9
12 QComboBox::~QComboBox() qcombobox.cpp 1465 0x101fd49ee
13 QComboBox::~QComboBox() qcombobox.cpp 1465 0x101fd49e9
14 QWidgetAction::~QWidgetAction() qwidgetaction.cpp 93 0x101f884ef
15 QWidgetAction::~QWidgetAction() qwidgetaction.cpp 85 0x101f8859e
16 QWidgetAction::~QWidgetAction() qwidgetaction.cpp 85 0x101f88599
17 QObjectPrivate::deleteChildren() qobject.cpp 2223 0x1033c7131
18 QWidget::~QWidget() qwidget.cpp 1563 0x101ecbec9
19 QToolBar::~QToolBar() qtoolbar.cpp 542 0x1020ceb5e
20 QToolBar::~QToolBar() qtoolbar.cpp 541 0x1020ceb59
21 QToolBar::~QToolBar() qtoolbar.cpp 541 0x1020ceb59
22 QObjectPrivate::deleteChildren() qobject.cpp 2223 0x1033c7131
23 QWidget::~QWidget() qwidget.cpp 1563 0x101ecbec9
24 ToolMainWindow::~ToolMainWindow() toolmainwindow.h 10 0x100306935
25 TextEdit::~TextEdit() textedit.cpp 139 0x1003d632c
26 TextEdit::~TextEdit() textedit.cpp 135 0x1003d6355
27 TextEdit::~TextEdit() textedit.cpp 135 0x1003d6399
28 QObjectPrivate::deleteChildren() qobject.cpp 2223 0x1033c7131
29 QWidget::~QWidget() qwidget.cpp 1563 0x101ecbec9
30 DockWidgetEx::~DockWidgetEx() dockwidgetex.h 10 0x10041e5a5
31 DockWidgetEx::~DockWidgetEx() dockwidgetex.h 10 0x10041e495
32 DockWidgetEx::~DockWidgetEx() dockwidgetex.h 10 0x10041e4b9
33 QObjectPrivate::deleteChildren() qobject.cpp 2223 0x1033c7131
34 QWidget::~QWidget() qwidget.cpp 1563 0x101ecbec9
35 MainWindow::~MainWindow() mainwindow.cpp 583 0x10032dc44
36 MainWindow::~MainWindow() mainwindow.cpp 578 0x10032dc65
37 MainWindow::~MainWindow() mainwindow.cpp 578 0x10032dca9
38 QObject::event(QEvent *) qobject.cpp 1416 0x1033c80a8
39 QWidget::event(QEvent *) qwidget.cpp 9413 0x101ee00f6
40 QMainWindow::event(QEvent *) qmainwindow.cpp 1315 0x10203368c
41 QApplicationPrivate::notify_helper(QObject *, QEvent *) qapplication.cpp 3301 0x101e850f4
42 QApplication::notify(QObject *, QEvent *) qapplication.cpp 0x101e8608e
43 QCoreApplication::notifyInternal2(QObject *, QEvent *) qcoreapplication.cpp 1106 0x10337bb83
44 QCoreApplication::sendEvent(QObject *, QEvent *) qcoreapplication.cpp 1546 0x10337bb17
45 QCoreApplicationPrivate::sendPostedEvents(QObject *, int, QThreadData *) qcoreapplication.cpp 1879 0x10337c349
46 QThreadPrivate::finish()::$_2::operator()() const qthread_unix.cpp 460 0x10352563f
47 void (anonymous namespace)::terminate_on_exception<QThreadPrivate::finish()::$_2>(QThreadPrivate::finish()::$_2&&) qthread_unix.cpp 365 0x1035255dd
48 QThreadPrivate::finish() qthread_unix.cpp 444 0x1035255dd
49 destroy_current_thread_data(QThreadData *) qthread_unix.cpp 171 0x103526653
50 (anonymous namespace)::QThreadDataDestroyer::EarlyMainThread::~EarlyMainThread() qthread_unix.cpp 230 0x103526637
51 (anonymous namespace)::QThreadDataDestroyer::EarlyMainThread::~EarlyMainThread() qthread_unix.cpp 227 0x103526624
52 __cxa_finalize_ranges (x86_64) /usr/lib/system/libsystem_c.dylib 0x7ff8091b8ea2
53 exit (x86_64) /usr/lib/system/libsystem_c.dylib 0x7ff8091b8cbd
54 -[NSApplication terminate:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cfe46a3
55 -[NSApplication _terminateFromSender:askIfShouldTerminate:saveWindows:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80d1418c0
56 -[NSApplication terminate:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cfe424d
57 QCocoaIntegration::quit() const qcocoaintegration.mm 442 0x102a02815
58 void doActivate<false>(QObject *, int, void * *) qobject.cpp 4150 0x1033d02b1
59 QGuiApplication::lastWindowClosed() moc_qguiapplication.cpp 318 0x101575362
60 QGuiApplicationPrivate::maybeLastWindowClosed() qguiapplication.cpp 3903 0x10157534f
61 QWindow::event(QEvent *) qwindow.cpp 2709 0x1015cfbac
62 QApplicationPrivate::notify_helper(QObject *, QEvent *) qapplication.cpp 3301 0x101e850f4
63 QApplication::notify(QObject *, QEvent *) qapplication.cpp 0x101e8608e
64 QCoreApplication::notifyInternal2(QObject *, QEvent *) qcoreapplication.cpp 1106 0x10337bc73
65 QCoreApplication::sendSpontaneousEvent(QObject *, QEvent *) qcoreapplication.cpp 1560 0x10337bc07
66 QGuiApplicationPrivate::processCloseEvent(QWindowSystemInterfacePrivate::CloseEvent *) qguiapplication.cpp 2909 0x10156dfc2
67 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *) qguiapplication.cpp 2257 0x10156dfba
68 bool QWindowSystemHelper<QWindowSystemInterface::SynchronousDelivery>::handleEvent<QWindowSystemInterfacePrivate::CloseEvent, QWindow *>(QWindow *) qwindowsysteminterface.cpp 105 0x1015dd696
69 QWindow::close() qwindow.cpp 2431 0x1015cee33
70 QApplicationPrivate::tryCloseAllWidgetWindows(QList<QWindow *> *) qapplication.cpp 1606 0x101e82fef
71 QApplication::closeAllWindows() qapplication.cpp 1635 0x101e833ac
72 QApplication::event(QEvent *) qapplication.cpp 1681 0x101e83394
73 QApplicationPrivate::notify_helper(QObject *, QEvent *) qapplication.cpp 3301 0x101e850f4
74 QApplication::notify(QObject *, QEvent *) qapplication.cpp 0x101e8608e
75 QCoreApplication::notifyInternal2(QObject *, QEvent *) qcoreapplication.cpp 1106 0x10337bc73
76 QCoreApplication::sendSpontaneousEvent(QObject *, QEvent *) qcoreapplication.cpp 1560 0x10337bc07
77 QGuiApplicationPrivate::processApplicationTermination(QWindowSystemInterfacePrivate::WindowSystemEvent *) qguiapplication.cpp 3961 0x10156d8b6
78 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent *) qguiapplication.cpp 2250 0x10156d880
79 bool QWindowSystemHelper<QWindowSystemInterface::SynchronousDelivery>::handleEvent<QWindowSystemInterfacePrivate::WindowSystemEvent, QWindowSystemInterfacePrivate::EventType>(QWindowSystemInterfacePrivate::EventType) qwindowsysteminterface.cpp 105 0x1015d8d01
80 bool handleWindowSystemEvent<QWindowSystemInterfacePrivate::WindowSystemEvent, QWindowSystemInterface::SynchronousDelivery, QWindowSystemInterfacePrivate::EventType>(QWindowSystemInterfacePrivate::EventType) qwindowsysteminterface.cpp 138 0x1015d8c86
81 bool QWindowSystemInterface::handleApplicationTermination<QWindowSystemInterface::SynchronousDelivery>() qwindowsysteminterface.cpp 281 0x1015d8c86
82 -[QCocoaApplicationDelegate applicationShouldTerminate:] qcocoaapplicationdelegate.mm 103 0x1029e9b26
83 -[NSApplication _docController:shouldTerminate:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cff46e0
84 __91-[NSDocumentController(NSInternal) _closeAllDocumentsWithDelegate:shouldTerminateSelector:]_block_invoke (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cff44dd
85 -[NSDocumentController(NSInternal) _closeAllDocumentsWithDelegate:shouldTerminateSelector:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cff3f83
86 -[NSDocumentController(NSInternal) __closeAllDocumentsWithDelegate:shouldTerminateSelector:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cff3961
87 -[NSApplication _shouldTerminate] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cff3411
88 -[NSApplication(NSAppleEventHandling) _handleAEQuit] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80d141531
89 -[NSApplication(NSAppleEventHandling) _handleCoreEvent:withReplyEvent:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cd8edfe
90 -[NSAppleEventManager dispatchRawAppleEvent:withRawReply:handlerRefCon:] (x86_64) /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation 0x7ff80a41ec81
91 _NSAppleEventManagerGenericHandler (x86_64) /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation 0x7ff80a41ea95
92 ___lldb_unnamed_symbol873 (x86_64) /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/AE.framework/Versions/A/AE 0x7ff810ba7d8e
93 ___lldb_unnamed_symbol872 (x86_64) /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/AE.framework/Versions/A/AE 0x7ff810ba75f1
94 aeProcessAppleEvent (x86_64) /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/AE.framework/Versions/A/AE 0x7ff810ba0ee6
95 AEProcessAppleEvent (x86_64) /System/Library/Frameworks/Carbon.framework/Versions/A/Frameworks/HIToolbox.framework/Versions/A/HIToolbox 0x7ff814d5e095
96 _DPSNextEvent (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cd8816a
97 -[NSApplication(NSEventRouting) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80d815997
98 -[NSApplication run] (x86_64) /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit 0x7ff80cd78f19
99 QCocoaEventDispatcher::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) qcocoaeventdispatcher.mm 374 0x1029f80a9
100 QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) qeventloop.cpp 104 0x103385236
101 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) qeventloop.cpp 186 0x103385218
102 QCoreApplication::exec() qcoreapplication.cpp 1449 0x10337b8ad
103 main main.cpp 214 0x1003100ee
104 start (x86_64) /usr/lib/dyld 0x7ff808f4a530