tdf#92386: Writer crashes in print preview if document in 2 windows

2 changes for the 2 following bts
First bt: see https://bugs.documentfoundation.org/attachment.cgi?id=116883
Second bt: see https://bugs.documentfoundation.org/attachment.cgi?id=116888

Change-Id: I92ed3b7305bb5b714532f2dcffd615a8337db8b6
Reviewed-on: https://gerrit.libreoffice.org/16557Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

sw/source/uibase/app/docsh.cxx

@@ -1261,11 +1261,15 @@ const ::sfx2::IXmlIdRegistry* SwDocShell::GetXmlIdRegistry() const
 
 bool SwDocShell::IsChangeRecording() const
 {
+    if (!m_pWrtShell)
+        return false;
     return (m_pWrtShell->GetRedlineMode() & nsRedlineMode_t::REDLINE_ON) != 0;
 }
 
 bool SwDocShell::HasChangeRecordProtection() const
 {
+    if (!m_pWrtShell)
+        return false;
     return m_pWrtShell->getIDocumentRedlineAccess()->GetRedlinePassword().getLength() > 0;
 }