xlrstatsplugin Error: unsupported operand type(s) for -: 'NoneType' and 'int'

I did a fresh install of the latest xlrstats (from xlr8or dev repo) deleting all previous xlr_* tables and creating tables with the xlrstats.sql file.
but I still hit this error :

Code:

100224 22:30:02 DEBUG PublistPlugin: Sending heartbeat to B3 master...
100224 22:30:02 VERBOSE RCON sending (91.121.95.52:27960) status
100224 22:30:02 BOT Starting Plugin xlrstats
100224 22:30:02 DEBUG AdminPlugin: Command "xlrhide (None)" registered with cmd_xlrhide for level (60, 100)
100224 22:30:02 DEBUG AdminPlugin: Command "xlrstats (None)" registered with cmd_xlrstats for level (1, 100)
100224 22:30:02 DEBUG AdminPlugin: Command "xlrtopstats (None)" registered with cmd_xlrtopstats for level (2, 100)
100224 22:30:02 DEBUG Register Event: Client Join Team: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Client Kill: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Client Team Kill: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Client Suicide: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Game Round Start: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Client Action: XlrstatsPlugin
100224 22:30:02 DEBUG Register Event: Client Damage: XlrstatsPlugin
100224 22:30:02 DEBUG XlrstatsPlugin: Got client id for WORLD: 6275
100224 22:30:02 VERBOSE XlrstatsPlugin: Checking if we need to update tables for version 2.0.0
100224 22:30:02 DEBUG XlrstatsPlugin: Optimizing Table(s): xlr_playerstats, xlr_weaponstats, xlr_weaponusage, xlr_bodyparts, xlr_playerbody, xlr_opponents, xlr_mapstats, xlr_playermaps, xlr_actionstats, xlr_playeractions
100224 22:30:02 DEBUG XlrstatsPlugin: Optimize Success
100224 22:30:02 DEBUG XlrstatsPlugin: Calculating kill_bonus
100224 22:30:02 INFO STDOUT Error: unsupported operand type(s) for -: 'NoneType' and 'int'
  File "/home/ubuteam/b3/__init__.py", line 160, in start
   console.start()
  File "/home/ubuteam/b3/parser.py", line 314, in start
   self.startPlugins()
  File "/home/ubuteam/b3/parser.py", line 533, in startPlugins
   p.onStartup()
  File "/home/ubuteam/b3/plugin.py", line 148, in onStartup
   self.startup()
  File "/home/ubuteam/b3-extplugins/xlrstats.py", line 201, in startup
   self.calculateKillBonus()
  File "/home/ubuteam/b3-extplugins/xlrstats.py", line 1437, in calculateKillBonus
   diff = max - self.defaultskill

100224 22:30:02 INFO STDOUT

100224 22:30:02 INFO STDOUT 223
100224 22:30:02 INFO STDOUT

100224 22:30:02 INFO HaxbusterurtPlugin: checking all new clients guid

I somewhat fixed that problem with:

Quote

q = 'SELECT MAX(skill) AS max_skill FROM %s' % self.playerstats_table
   cursor = self.query(q)
   r = cursor.getRow()
   max = r['max_skill']
   if max is None:
   max = self.defaultskill
   diff = max - self.defaultskill
   if diff < 0:
   self.kill_bonus = 2.0

but I'm not sure is this is a clever default value