tdf#107350 - prevent crash in unotbl.cxx

check pointer and throw exception instead of SIGABRT
when reading data from text tables that have
varying row &/or col lengths from
 - merged cells after first row,
 - split cells in first row, etc.

add backstop safety check -> exception because
 - complexity check fails (wrong/not called)
 - OOo uno api doc calls for exception when
       text table is 'too complex'
v2:  better error message for crash point and
       its parallel (getData[Array])

Change-Id: Ifb844c3e29042dab6b6cdb2448f7728e6ccb631d
Reviewed-on: https://gerrit.libreoffice.org/37002Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Björn Michaelsen <bjoern.michaelsen@libreoffice.org>

sw/source/core/unocore/unotbl.cxx

@@ -3621,7 +3621,7 @@ uno::Sequence<uno::Sequence<uno::Any>> SAL_CALL SwXCellRange::getDataArray()
         {
             auto pCell(static_cast<SwXCell*>(pCurrentCell->get()));
             if(!pCell)
-                throw uno::RuntimeException();
+                throw uno::RuntimeException("Table too complex", static_cast<cppu::OWeakObject*>(this));
             rCellAny = pCell->GetAny();
             ++pCurrentCell;
         }
@@ -3688,6 +3688,8 @@ SwXCellRange::getData()
         rRow = uno::Sequence<double>(nColCount);
         for(auto& rValue : rRow)
         {
+            if(!(*pCurrentCell))
+                throw uno::RuntimeException("Table too complex", static_cast<cppu::OWeakObject*>(this));
             rValue = (*pCurrentCell)->getValue();
             ++pCurrentCell;
         }