silence warning when resolving team for self-damage

main.py

@@ -54,7 +54,7 @@ def team(player: str) -> str:
     if player in TEAMS:
         return TEAMS[player]
     else:
-        if not player in _logged_teams:
+        if not player in _logged_teams and player:
             LOG.warning(f"missing team mapping for {player}")
         _logged_teams.append(player)
         return player