Error message in my console : [Netty Epoll Server IO #1/WARN]: [OldCombatMechanics] playerWeakReference or its value is null. This should NOT happen at this stage.Please report the error on github. (read)

How to solve the problem?

• Server version: 1.12
• OldCombatMechanics version: 1.6.6
• config : https://pastebin.com/B8ZhpV44

Duplicate of #248. Please use the latest test version from here.