TypeError: cannot concatenate 'str' and 'NoneType' objects

[aamd@…]

How to Reproduce

While doing a POST operation on /admin/ganttcalendar/holiday, Trac issued an internal error.

(please provide additional details here)

Request parameters:

{'__FORM_TOKEN': u'f95e5d5f7ec6c565155ec63a',
 'cat_id': u'ganttcalendar',
 'create_table': u'Create table and insert some holidays.',
 'panel_id': u'holiday',
 'path_info': None}

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/537.22 (KHTML, like Gecko) Chrome/25.0.1364.160 Safari/537.22

System Information

Trac	1.0
Babel	0.9.5
Docutils	0.6
Genshi	0.6 (without speedups)
psycopg2	2.4.4
Python	2.6.6 (r266:84292, Feb 22 2013, 00:00:18) [GCC 4.4.7 20120313 (Red Hat 4.4.7-3)]
setuptools	0.6
Subversion	1.6.11 (r934486)
jQuery	1.7.2

Enabled Plugins

SimpleMultiProject	0.0.3dev-r12347
timingandestimationplugin	1.2.8
Trac-jsGantt	0.10-r12330
TracAccountManager	0.3.2
TracGanttCalendarPlugin	0.6.2-r820
TracMasterTickets	3.0.3

Python Traceback

Traceback (most recent call last):
  File "/home/codekim/webapps/tracfiscalgennesys/lib/python2.6/Trac-1.0-py2.6.egg/trac/web/main.py", line 497, in _dispatch_request
    dispatcher.dispatch(req)
  File "/home/codekim/webapps/tracfiscalgennesys/lib/python2.6/Trac-1.0-py2.6.egg/trac/web/main.py", line 214, in dispatch
    resp = chosen_handler.process_request(req)
  File "/home/codekim/webapps/tracfiscalgennesys/lib/python2.6/Trac-1.0-py2.6.egg/trac/admin/web_ui.py", line 125, in process_request
    path_info)
  File "/home/codekim/webapps/tracfiscalgennesys/plugins/TracGanttCalendarPlugin-0.6.2_r820-py2.6.egg/ganttcalendar/admin.py", line 76, in render_admin_panel
    self.log.info("loc:"+loc)
TypeError: cannot concatenate 'str' and 'NoneType' objects

[Remy Blank]

PluginIssue (TracGanttCalendarPlugin).