TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

[Christian Boos]

I've updated the SpamFilter to 0.4.3dev (r10360) on ​http://trac.edgewall.org/demo-0.13. In the Bayes admin panel, submitting some spam or ham yields the following backtrace…

How to Reproduce

While doing a POST operation on /admin/spamfilter/bayes, Trac issued an internal error.

(please provide additional details here)

Request parameters:

{'__FORM_TOKEN': u'b2d08ba806dad9207fe002c8',
 'cat_id': u'spamfilter',
 'content': u'this is a test...',
 'min_training': u'25',
 'panel_id': u'bayes',
 'path_info': None,
 'train': u'Train as Ham'}

User agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.10 (KHTML, like Gecko) Chrome/8.0.552.215 Safari/534.10

System Information

Trac	0.13dev-r10358
Babel	0.9.5
Docutils	0.6
Genshi	0.7dev-r1134
GIT	1.7.1.rc1.21.gf3bd6
Mercurial	1.7
Pygments	1.3.1dev-20100812
pysqlite	2.5.6
Python	2.5.2 (r252:60911, Oct 5 2008, 19:49:54) [GCC 4.3.2]
setuptools	0.6c9
SQLite	3.6.20
Subversion	1.5.1 (r32289)
jQuery	1.4.3

Enabled Plugins

TracGit	0.12.0.5dev
TracMercurial	0.13.0.1dev-r10329
TracSpamFilter	0.4.3dev-r10360

Python Traceback

Traceback (most recent call last):
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 511, in _dispatch_request
    dispatcher.dispatch(req)
  File "build/bdist.linux-x86_64/egg/trac/web/main.py", line 237, in dispatch
    resp = chosen_handler.process_request(req)
  File "build/bdist.linux-x86_64/egg/trac/admin/web_ui.py", line 122, in process_request
    path_info)
  File "/usr/local/virtualenv/0.13dev/lib/python2.5/site-packages/TracSpamFilter-0.4.3dev_r10360-py2.5.egg/tracspamfilter/admin.py", line 351, in render_admin_panel
    spam='spam' in req.args['train'].lower())
  File "/usr/local/virtualenv/0.13dev/lib/python2.5/site-packages/TracSpamFilter-0.4.3dev_r10360-py2.5.egg/tracspamfilter/filters/bayes.py", line 75, in train
    testcontent = author+"\n"+content
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

author was None.