fix leave parser returning undefined instead of null for missing player

Author: Meshiest

parsers/leave.js

@@ -26,7 +26,8 @@ class LeaveParser extends BaseParser {
         if (!match)
             return null;
 
-        return this._brikkit._players.find(p => p._controller === match[1]);
+        const player = this._brikkit._players.find(p => p._controller === match[1]);
+        return player !== undefined ? player : null;
     }
 }