the main text format is not a trailing text format, tdf#92457 follow-up

Change-Id: I91d5a2ff9fb59b68b28dec0ed8b2802782e28727

svl/source/numbers/zformat.cxx

@@ -943,7 +943,7 @@ SvNumberformat::SvNumberformat(OUString& rString,
                             sBuff.insert(nPos, ";");
                             nPos++;
                         }
-                        else
+                        else if (nIndex > 0)
                         {
                             // The last subformat. If it is a trailing text
                             // format the omitted subformats act like they were