How to reproduce:

Start PulseView (with an LA attached), click on any probe, then click on any of the triggering icons (rising, falling, low, high, etc) -> segfault.

Backtrace:

(gdb) bt
#0  pv::view::LogicSignal::match_action (this=this@entry=0xf90150, type=0x0)
    at [...]/pulseview/pv/view/logicsignal.cpp:261
#1  0x000000000046fa95 in pv::view::LogicSignal::on_trigger (this=0xf90150)
    at [...]/pulseview/pv/view/logicsignal.cpp:334
#2  0x00007f474cbbc90d in QMetaObject::activate (sender=sender@entry=0xfde4d0, 
    signalOffset=<optimized out>, 
    local_signal_index=local_signal_index@entry=1, 
    argv=argv@entry=0x7fffdd493310) at kernel/qobject.cpp:3681
#3  0x00007f474cbbcd77 in QMetaObject::activate (sender=sender@entry=0xfde4d0, 
    m=m@entry=0x7f474f15a500 <QAction::staticMetaObject>, 
    local_signal_index=local_signal_index@entry=1, 
    argv=argv@entry=0x7fffdd493310) at kernel/qobject.cpp:3547
#4  0x00007f474ea6f732 in QAction::triggered (this=this@entry=0xfde4d0, 
    _t1=true) at .moc/moc_qaction.cpp:359
#5  0x00007f474ea71db8 in QAction::activate (this=0xfde4d0, 
    event=<optimized out>) at kernel/qaction.cpp:1175
#6  0x00007f474eb7264d in QAbstractButtonPrivate::click (this=0xfd63b0)
    at widgets/qabstractbutton.cpp:524
#7  0x00007f474eb72864 in QAbstractButton::mouseReleaseEvent (this=0xfd6960, e=
    0x7fffdd493820) at widgets/qabstractbutton.cpp:1140
#8  0x00007f474ec3b00a in QToolButton::mouseReleaseEvent (
---Type <return> to continue, or q <return> to quit---
    this=<optimized out>, e=<optimized out>) at widgets/qtoolbutton.cpp:616
#9  0x00007f474eab5148 in QWidget::event (this=0xfd6960, event=0x7fffdd493820)
    at kernel/qwidget.cpp:8316
#10 0x00007f474eb73f13 in QAbstractButton::event (this=this@entry=0xfd6960, 
    e=e@entry=0x7fffdd493820) at widgets/qabstractbutton.cpp:1097
#11 0x00007f474ec3b0e9 in QToolButton::event (this=0xfd6960, 
    event=0x7fffdd493820) at widgets/qtoolbutton.cpp:965
#12 0x00007f474ea76f3c in QApplicationPrivate::notify_helper (this=0xbcc130, 
    receiver=0xfd6960, e=0x7fffdd493820) at kernel/qapplication.cpp:3499
#13 0x00007f474ea7c97c in QApplication::notify (this=0xfd6960, receiver=0x0, 
    e=0x7fffdd493820) at kernel/qapplication.cpp:3066
#14 0x000000000043c1e6 in Application::notify (this=<optimized out>, 
    receiver=<optimized out>, event=<optimized out>)
    at [...]/pulseview/pv/application.cpp:38
#15 0x00007f474cb8df1b in QCoreApplication::notifyInternal (this=
    0x7fffdd494090, receiver=receiver@entry=0xfd6960, 
    event=event@entry=0x7fffdd493820) at kernel/qcoreapplication.cpp:935
#16 0x00007f474ea7b11a in sendSpontaneousEvent (event=0x7fffdd493820, 
    receiver=0xfd6960)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:240
#17 QApplicationPrivate::sendMouseEvent (receiver=0xfd6960, 
    event=0x7fffdd493820, alienWidget=0xfd6960, nativeWidget=0xe94520, 
---Type <return> to continue, or q <return> to quit---
    buttonDown=<optimized out>, lastMouseReceiver=..., spontaneous=true)
    at kernel/qapplication.cpp:2539
#18 0x00007f474ead3754 in QWidgetWindow::handleMouseEvent (this=0xfd6350, 
    event=0x7fffdd493c50) at kernel/qwidgetwindow.cpp:411
#19 0x00007f474ead5dd3 in QWidgetWindow::event (this=0xfd6350, 
    event=0x7fffdd493c50) at kernel/qwidgetwindow.cpp:179
#20 0x00007f474ea76f3c in QApplicationPrivate::notify_helper (this=0xbcc130, 
    receiver=0xfd6350, e=0x7fffdd493c50) at kernel/qapplication.cpp:3499
#21 0x00007f474ea7c380 in QApplication::notify (this=0x7fffdd494090, 
    receiver=0xfd6350, e=0x7fffdd493c50) at kernel/qapplication.cpp:3282
#22 0x000000000043c1e6 in Application::notify (this=<optimized out>, 
    receiver=<optimized out>, event=<optimized out>)
    at [...]/pulseview/pv/application.cpp:38
#23 0x00007f474cb8df1b in QCoreApplication::notifyInternal (
    this=0x7fffdd494090, receiver=0xfd6350, event=0x7fffdd493c50)
    at kernel/qcoreapplication.cpp:935
#24 0x00007f474f26c5c3 in sendSpontaneousEvent (event=<optimized out>, 
    receiver=<optimized out>)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:240
#25 QGuiApplicationPrivate::processMouseEvent (e=0xfdb1a0)
    at kernel/qguiapplication.cpp:1748
#26 0x00007f474f26de25 in QGuiApplicationPrivate::processWindowSystemEvent (
---Type <return> to continue, or q <return> to quit---
    e=e@entry=0xfdb1a0) at kernel/qguiapplication.cpp:1549
#27 0x00007f474f25355f in QWindowSystemInterface::sendWindowSystemEvents (
    flags=...) at kernel/qwindowsysteminterface.cpp:579
#28 0x00007f4744d05f50 in userEventSourceDispatch (source=<optimized out>)
    at eventdispatchers/qeventdispatcher_glib.cpp:78
#29 0x00007f474da91c5d in g_main_dispatch (context=0x7f473c0016f0)
    at /build/glib2.0-dt6trg/glib2.0-2.42.0/./glib/gmain.c:3111
#30 g_main_context_dispatch (context=context@entry=0x7f473c0016f0)
    at /build/glib2.0-dt6trg/glib2.0-2.42.0/./glib/gmain.c:3710
#31 0x00007f474da91f48 in g_main_context_iterate (
    context=context@entry=0x7f473c0016f0, block=block@entry=1, 
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/glib2.0-dt6trg/glib2.0-2.42.0/./glib/gmain.c:3781
#32 0x00007f474da91ffc in g_main_context_iteration (context=0x7f473c0016f0, 
    may_block=1) at /build/glib2.0-dt6trg/glib2.0-2.42.0/./glib/gmain.c:3842
#33 0x00007f474cbe5537 in QEventDispatcherGlib::processEvents (this=0xbfe510, 
    flags=...) at kernel/qeventdispatcher_glib.cpp:426
#34 0x00007f474cb8b752 in QEventLoop::exec (this=this@entry=0x7fffdd493ff0, 
    flags=..., flags@entry=...) at kernel/qeventloop.cpp:212
#35 0x00007f474cb931cc in QCoreApplication::exec ()
    at kernel/qcoreapplication.cpp:1188
#36 0x00007f474f26419c in QGuiApplication::exec ()
    at kernel/qguiapplication.cpp:1483
---Type <return> to continue, or q <return> to quit---
#37 0x00007f474ea75595 in QApplication::exec () at kernel/qapplication.cpp:2744
#38 0x000000000043ab6e in main (argc=1, argv=<optimized out>)
    at [...]/pulseview/main.cpp:164