ndiff crashes when its called with not nmap files

Binary package hint: nmap

steps to reproduce:
noone@neo:~/tmp/c$cat foo && cat bar
1
2
noone@neo:~/tmp/c$ndiff foo bar
Traceback (most recent call last):
  File "/usr/bin/ndiff", line 1036, in <module>
    main()
  File "/usr/bin/ndiff", line 1024, in main
    scan_a.load_from_file(filename_a)
  File "/usr/bin/ndiff", line 56, in load_from_file
    self.load(f)
  File "/usr/bin/ndiff", line 50, in load
    parser.parse(f)
  File "/usr/lib/python2.6/xml/sax/expatreader.py", line 107, in parse
    xmlreader.IncrementalParser.parse(self, source)
  File "/usr/lib/python2.6/xml/sax/xmlreader.py", line 123, in parse
    self.feed(buffer)
  File "/usr/lib/python2.6/xml/sax/expatreader.py", line 211, in feed
    self._err_handler.fatalError(exc)
  File "/usr/lib/python2.6/xml/sax/handler.py", line 38, in fatalError
    raise exception
xml.sax._exceptions.SAXParseException: foo:1:0: syntax error

im missing some errormessages if ndiff is called with files in the wrong format.

ProblemType: Bug
Architecture: i386
Date: Wed Dec 2 23:11:33 2009
DistroRelease: Ubuntu 9.10
Package: nmap 5.00-2
ProcEnviron:
 LANGUAGE=de_DE.UTF-8
 PATH=(custom, user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
ProcVersionSignature: Ubuntu 2.6.31-15.50-generic
SourcePackage: nmap
Uname: Linux 2.6.31-15-generic i686