handle error when an object was not found in dumpxml()
handle error when an object was not found in dumpxml()


git-svn-id: f1daae93ec50fd93b15e4810276f299070365e28@92 1aa58f4a-7d42-0410-adbc-911cccaed67c

euske/pdfminer,rotula/pdfminer,goulu/pdfminer,pdfminer/pdfminer.six