cid#1660799 silence Dereference null return value

Change-Id: I7392878e4e17bc70d11c13122bd657ad5a531dd4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/188887
Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Tested-by: Jenkins

include/svx/numfmtsh.hxx

@@ -227,6 +227,8 @@ private:
                                                 const Color*& rpColor );
     SVX_DLLPRIVATE static void PosToCategory_Impl(sal_uInt16 nPos, SvNumFormatType& rCategory);
     SVX_DLLPRIVATE static void CategoryToPos_Impl(SvNumFormatType nCategory, sal_uInt16& rPos);
+
+    SVX_DLLPRIVATE bool IsNotNatNum12(short nEntry) const;
 };
 
 #endif

svx/source/items/numfmtsh.cxx

@@ -1328,6 +1328,12 @@ bool SvxNumberFormatShell::GetUserDefined4Entry(short nEntry)
     return false;
 }
 
+bool SvxNumberFormatShell::IsNotNatNum12(short nEntry) const
+{
+    const SvNumberformat* pNumEntry = pFormatter->GetEntry(aCurEntryList[nEntry]);
+    return !pNumEntry || pNumEntry->GetFormatstring().indexOf("NatNum12") < 0;
+}
+
 /*
  * Function:   Returns the format string for a given entry.
  * Input:      Number of the entry
@@ -1338,10 +1344,7 @@ OUString SvxNumberFormatShell::GetFormat4Entry(short nEntry)
     if (nEntry < 0)
         return OUString();
 
-    if (!aCurrencyFormatList.empty()
-        && (!pFormatter->GetEntry(aCurEntryList[nEntry])
-            || pFormatter->GetEntry(aCurEntryList[nEntry])->GetFormatstring().indexOf("NatNum12")
-                   < 0))
+    if (!aCurrencyFormatList.empty() && IsNotNatNum12(nEntry))
     {
         if (aCurrencyFormatList.size() > o3tl::make_unsigned(nEntry))
             return aCurrencyFormatList[nEntry];