It's not possible to run bui-agent without -v option

$ bui-agent -c x 
Traceback (most recent call last):
  File "/usr/bin/bui-agent", line 9, in <module>
    load_entry_point('burp-ui==0.3.0', 'console_scripts', 'bui-agent')()
  File "/usr/lib/python3.5/site-packages/burpui/__main__.py", line 108, in agent
    agent = Agent(conf, options.log, options.logfile, options.debug)
  File "/usr/lib/python3.5/site-packages/burpui/agent.py", line 98, in __init__
    if level > logging.NOTSET:
TypeError: unorderable types: NoneType() > int()

$ bui-agent -vc x works.