When there are no milestones in trac, the burndown page does not display a graceful "there are no milestones" page, but instead breaks:
Traceback (most recent call last):
File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 387, in dispatch_request
dispatcher.dispatch(req)
File "/usr/lib/python2.3/site-packages/trac/web/main.py", line 237, in dispatch
resp = chosen_handler.process_request(req)
File "/usr/lib/python2.3/site-packages/TracBurndown-0.1-py2.3.egg/burndown/burndown.py", line 122, in process_request
selected_milestone = req.args.get('selected_milestone', milestones[0])
IndexError: list index out of range