Assistant crashes when doing search

Thread 0:: Dispatch queue: com.apple.main-thread
0 libsystem_kernel.dylib 0x00007fff5a860cee __psynch_cvwait + 10
1 libsystem_pthread.dylib 0x00007fff5a99d662 _pthread_cond_wait + 732
2 org.qt-project.QtCore 0x000000010f614a2b QWaitConditionPrivate::wait(unsigned long) + 75
3 org.qt-project.QtCore 0x000000010f6149c2 QWaitCondition::wait(QMutex*, unsigned long) + 162
4 org.qt-project.QtCore 0x000000010f61416e QThread::wait(unsigned long) + 110
5 org.qt-project.QtHelp 0x000000010eb0f7d3 fulltextsearch::QHelpSearchIndexReader::search(QString const&, QString const&, QString const&) + 35
6 org.qt-project.QtHelp 0x000000010eb04655 QHelpSearchEnginePrivate::search(QString const&) + 821
7 org.qt-project.assistant 0x000000010e9e9391 0x10e9b1000 + 230289
8 org.qt-project.QtCore 0x000000010f7f5e1b QMetaObject::activate(QObject*, int, int, void**) + 2347
9 org.qt-project.QtCore 0x000000010f7f5e1b QMetaObject::activate(QObject*, int, int, void**) + 2347
10 org.qt-project.QtWidgets 0x000000010ec41fbf QAbstractButtonPrivate::emitClicked() + 111
11 org.qt-project.QtWidgets 0x000000010ec41e52 QAbstractButtonPrivate::click() + 226
12 org.qt-project.QtWidgets 0x000000010ec430bf QAbstractButton::mouseReleaseEvent(QMouseEvent*) + 271
13 org.qt-project.QtWidgets 0x000000010eb822b0 QWidget::event(QEvent*) + 496
14 org.qt-project.QtWidgets 0x000000010ec42c21 QAbstractButton::event(QEvent*) + 145
15 org.qt-project.QtWidgets 0x000000010eb48152 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 306
16 org.qt-project.QtWidgets 0x000000010eb4aeed QApplication::notify(QObject*, QEvent*) + 7165
17 org.qt-project.QtCore 0x000000010f7c4d6f QCoreApplication::notifyInternal2(QObject*, QEvent*) + 159
18 org.qt-project.QtWidgets 0x000000010eb48a80 QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) + 896
19 org.qt-project.QtWidgets 0x000000010eba23f0 QWidgetWindow::handleMouseEvent(QMouseEvent*) + 1744
20 org.qt-project.QtWidgets 0x000000010eba10e0 QWidgetWindow::event(QEvent*) + 224
21 org.qt-project.QtWidgets 0x000000010eb48152 QApplicationPrivate::notify_helper(QObject*, QEvent*) + 306
22 org.qt-project.QtWidgets 0x000000010eb4946f QApplication::notify(QObject*, QEvent*) + 383
23 org.qt-project.QtCore 0x000000010f7c4d6f QCoreApplication::notifyInternal2(QObject*, QEvent*) + 159
24 org.qt-project.QtGui 0x000000010f105209 QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 3145
25 org.qt-project.QtGui 0x000000010f0eb5eb QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 155
26 libqcocoa.dylib 0x0000000111816091 QCocoaEventDispatcherPrivate::postedEventsSourceCallback(void*) + 33
27 com.apple.CoreFoundation 0x00007fff32e2c5a1 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
28 com.apple.CoreFoundation 0x00007fff32ee635c __CFRunLoopDoSource0 + 108
29 com.apple.CoreFoundation 0x00007fff32e0f040 __CFRunLoopDoSources0 + 208
30 com.apple.CoreFoundation 0x00007fff32e0e4bd __CFRunLoopRun + 1293
31 com.apple.CoreFoundation 0x00007fff32e0dd23 CFRunLoopRunSpecific + 483
32 com.apple.HIToolbox 0x00007fff32125e26 RunCurrentEventLoopInMode + 286
33 com.apple.HIToolbox 0x00007fff32125a9f ReceiveNextEventCommon + 366
34 com.apple.HIToolbox 0x00007fff32125914 _BlockUntilNextEventMatchingListInModeWithFilter + 64
35 com.apple.AppKit 0x00007fff303f0f5f _DPSNextEvent + 2085
36 com.apple.AppKit 0x00007fff30b86b4c -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 3044
37 com.apple.AppKit 0x00007fff303e5d6d -[NSApplication run] + 764
38 libqcocoa.dylib 0x0000000111814e8d QCocoaEventDispatcher::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) + 2397
39 org.qt-project.QtCore 0x000000010f7c08c2 QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) + 418
40 org.qt-project.QtCore 0x000000010f7c5482 QCoreApplication::exec() + 402
41 org.qt-project.assistant 0x000000010e9d3e46 0x10e9b1000 + 142918
42 libdyld.dylib 0x00007fff5a711115 start + 1