These items are of type SfxUInt32Item

...see include/svx/svxids.hrc for SID_ATTR_NUMBERFORMAT_VALUE and
chart2/source/inc/chartview/ChartSfxItemIds.hxx for
SCHATTR_AXIS_CROSSING_MAIN_AXIS_NUMBERFORMAT, and as reported by
-fsanitize=vptr in sc/qa/uitest/chart/tdf122398.py recently added to
UITest_chart (<https://ci.libreoffice.org/job/lo_ubsan/1188/>).

Change-Id: Ic1e2f3390bd54b722730e6dd7962d613587774b1
Reviewed-on: https://gerrit.libreoffice.org/67884
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

chart2/source/controller/dialogs/tp_AxisPositions.cxx

@@ -243,7 +243,7 @@ void AxisPositionsTabPage::SetNumFormatter( SvNumberFormatter* pFormatter )
     const SfxPoolItem *pPoolItem = nullptr;
     if( GetItemSet().GetItemState( SCHATTR_AXIS_CROSSING_MAIN_AXIS_NUMBERFORMAT, true, &pPoolItem ) == SfxItemState::SET )
     {
-        sal_uLong nFmt = static_cast<sal_uLong>(static_cast<const SfxInt32Item*>(pPoolItem)->GetValue());
+        sal_uLong nFmt = static_cast<const SfxUInt32Item*>(pPoolItem)->GetValue();
         m_xED_CrossesAt->set_format_key( nFmt );
     }
 }

chart2/source/controller/dialogs/tp_Scale.cxx

@@ -500,7 +500,7 @@ void ScaleTabPage::SetNumFormat()
 
     if( GetItemSet().GetItemState( SID_ATTR_NUMBERFORMAT_VALUE, true, &pPoolItem ) == SfxItemState::SET )
     {
-        sal_uLong nFmt = static_cast<sal_uLong>(static_cast<const SfxInt32Item*>(pPoolItem)->GetValue());
+        sal_uLong nFmt = static_cast<const SfxUInt32Item*>(pPoolItem)->GetValue();
 
         m_xFmtFldMax->set_format_key(nFmt);
         m_xFmtFldMin->set_format_key(nFmt);