tdf#159213: fix Base crash when choosing "Help" in relations design (kf5)

There are 2 parts here:
1) in vcl/qt5:
- for release versions: avoid to call QtAccessibleRegistry::getQObject on a null object
- for debug version: add an assertion on object to check it's not null

2) in svtools:
the specific root cause  was in EditBrowseBox::DeactivateCell,
we must check m_aImpl->m_xActiveCell in addition to isAccessibleAlive()

Import remark: I had a very naive/bandaid patch at the beginning
this one is entirely thanks to Michael Weghorn

Change-Id: I90214e9c5b7c0aa45481915d7be6020a7dc8c42e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/162182
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins
(cherry picked from commit 1a637a07a0fb23f4d4bfac69378caff7ee965737)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/162141

1 files changed, 10 insertions, 0 deletions

diff --git a/vcl/qt5/QtAccessibleEventListener.cxx b/vcl/qt5/QtAccessibleEventListener.cxx
index d6a404e6947e..0bf4dcddbf2d 100644
--- a/vcl/qt5/QtAccessibleEventListener.cxx
+++ b/vcl/qt5/QtAccessibleEventListener.cxx
@@ -213,12 +213,22 @@ void QtAccessibleEventListener::notifyEvent(const css::accessibility::Accessible
             Reference<XAccessible> xChild;
             if (aEvent.NewValue >>= xChild)
             {
+                assert(xChild.is()
+                       && "AccessibleEventId::CHILD event NewValue without valid child set");
+                // tdf#159213 for now, workaround invalid events being sent and don't crash in release builds
+                if (!xChild.is())
+                    return;
                 QAccessible::updateAccessibility(new QAccessibleEvent(
                     QtAccessibleRegistry::getQObject(xChild), QAccessible::ObjectCreated));
                 return;
             }
             if (aEvent.OldValue >>= xChild)
             {
+                assert(xChild.is()
+                       && "AccessibleEventId::CHILD event OldValue without valid child set");
+                // tdf#159213 for now, workaround invalid events being sent and don't crash in release builds
+                if (!xChild.is())
+                    return;
                 QAccessible::updateAccessibility(new QAccessibleEvent(
                     QtAccessibleRegistry::getQObject(xChild), QAccessible::ObjectDestroyed));
                 return;