tdf#127955 check if position stored in user config is in range for the treeview

https://crashreport.libreoffice.org/stats/crash_details/8c4a3136-73be-4536-ad6f-ce97ae0368dd

Change-Id: I320f965eb622f90f8059f85e7ba2ff203419ab3f
Reviewed-on: https://gerrit.libreoffice.org/84601
Tested-by: Jenkins
Reviewed-by: Michael Stahl <michael.stahl@cib.de>
diff --git a/sw/source/ui/fldui/fldref.cxx b/sw/source/ui/fldui/fldref.cxx
index 3a62dd54..6bddaaa 100644
--- a/sw/source/ui/fldui/fldref.cxx
+++ b/sw/source/ui/fldui/fldref.cxx
@@ -258,7 +258,7 @@ void SwFieldRefPage::Reset(const SfxItemSet* )
        }
    }
    TypeHdl(*m_xTypeLB);
    if(nFormatBoxPosition != USHRT_MAX)
    if (nFormatBoxPosition < m_xFormatLB->n_children())
    {
        m_xFormatLB->select(nFormatBoxPosition);
    }