how to fix this?
[04:30:23 ERROR]: [MythicMobs] [SCHEDULER] Exception thrown whilst executing task [04:30:23 WARN]: java.lang.NullPointerException: Cannot invoke "io.lumine.mythic.core.skills.variables.VariableRegistry.clean()" because the return value of "io.lumine.mythic.utils.serialization.WrappedJsonFile.get()" is null [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.core.skills.variables.VariableManager.save(VariableManager.java:52) [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.core.config.ConfigManager.save(ConfigManager.java:153) [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.bukkit.clock.MythicClock.executeSave(MythicClock.java:115) [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.bukkit.clock.MythicClock.runSavingClock(MythicClock.java:77) [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.utils.Delegates$RunnableToConsumer.accept(Delegates.java:93) [04:30:23 WARN]: at MythicMobs-5.0.2.jar//io.lumine.mythic.utils.Schedulers$LumineTask.run(Schedulers.java:162) [04:30:23 WARN]: at org.bukkit.craftbukkit.v1_18_R2.scheduler.CraftTask.run(CraftTask.java:101) [04:30:23 WARN]: at org.bukkit.craftbukkit.v1_18_R2.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:483) [04:30:23 WARN]: at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1559) [04:30:23 WARN]: at net.minecraft.server.dedicated.DedicatedServer.b(DedicatedServer.java:522) [04:30:23 WARN]: at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1483) [04:30:23 WARN]: at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:1247) [04:30:23 WARN]: at net.minecraft.server.MinecraftServer.lambda$spin$1(MinecraftServer.java:321) [04:30:23 WARN]: at java.base/java.lang.Thread.run(Thread.java:833)