ajLeaderboards and DynamicDifficulty on join problem

[cupang-afk]

you can see the log

it happens every time player join, it doesn't hurt or affect both plugins though

[08:09:17 WARN]: [ajLeaderboards] Placeholder %dd_user_affinity% for player cupang_afk threw an error:
java.lang.NullPointerException: Cannot invoke "me.skinnyjeans.gmd.models.Minecrafter.getAffinity()" because the return value of "me.skinnyjeans.gmd.managers.PlayerManager.getPlayerAffinity(java.util.UUID)" is null
        at DynamicDifficulty [1.8].jar/me.skinnyjeans.gmd.hooks.PlaceholderAPIExpansion.placeholderRequest(PlaceholderAPIExpansion.java:53) ~[DynamicDifficulty [1.8].jar:?]
        at DynamicDifficulty [1.8].jar/me.skinnyjeans.gmd.hooks.PlaceholderAPIExpansion.onRequest(PlaceholderAPIExpansion.java:45) ~[DynamicDifficulty [1.8].jar:?]
        at PlaceholderAPI [2.11.7-DEV-200].jar/me.clip.placeholderapi.replacer.CharsReplacer.apply(CharsReplacer.java:119) ~[PlaceholderAPI [2.11.7-DEV-200].jar:?]
        at PlaceholderAPI [2.11.7-DEV-200].jar/me.clip.placeholderapi.PlaceholderAPI.setPlaceholders(PlaceholderAPI.java:71) ~[PlaceholderAPI [2.11.7-DEV-200].jar:?]
        at ajLeaderboards [2.9.0].jar/us.ajg0702.leaderboards.cache.Cache.updateStat(Cache.java:546) ~[ajLeaderboards [2.9.0].jar:?]
        at ajLeaderboards [2.9.0].jar/us.ajg0702.leaderboards.cache.Cache.updatePlayerStats(Cache.java:500) ~[ajLeaderboards [2.9.0].jar:?]
        at ajLeaderboards [2.9.0].jar/us.ajg0702.leaderboards.Listeners.lambda$onJoin$1(Listeners.java:40) ~[ajLeaderboards [2.9.0].jar:?]
        at org.bukkit.craftbukkit.scheduler.CraftTask.run(CraftTask.java:78) ~[purpur-1.21.3.jar:1.21.3-2358-16ce24a]
        at org.bukkit.craftbukkit.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:57) ~[purpur-1.21.3.jar:1.21.3-2358-16ce24a]
        at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[purpur-1.21.3.jar:?]
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
        at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]