Hỏi đáp Lỗi plugin Mythicmobs generated an exception

[MythicMobs] Task #19175 for MythicMobs v4.4.0 generated an exception
java.lang.NullPointerException: null
at me.libraryaddict.disguise.disguisetypes.Disguise.setWatcher(Disguise.java:701) ~[?:?]
at me.libraryaddict.disguise.disguisetypes.PlayerDisguise.setWatcher(PlayerDisguise.java:335) ~[?:?]
at me.libraryaddict.disguise.disguisetypes.PlayerDisguise.clone(PlayerDisguise.java:112) ~[?:?]
at me.libraryaddict.disguise.disguisetypes.PlayerDisguise.clone(PlayerDisguise.java:15) ~[?:?]
at me.libraryaddict.disguise.DisguiseAPI.disguiseToAll(DisguiseAPI.java:255) ~[?:?]
at io.lumine.xikage.mythicmobs.compatibility.LibsDisguisesSupport$1.run(LibsDisguisesSupport.java:138) ~[?:?]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:76) ~[spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:361) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:739) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [spigot-1.12.2.jar:git-Spigot-2cf50f0-2b93d83]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_181]
[11:44:03 WARN]: [MythicMobs] Task #19179 for MythicMobs v4.4.0 generated an exception
java.lang.NullPointerException: null
at me.libraryaddict.disguise.disguisetypes.Disguise.setWatcher(Disguise.java:701) ~[?:?]
at me.libraryaddict.disguise.disguisetypes.PlayerDisguise.setWatcher(PlayerDisguise.java:335) ~[?:?]
Các bác cho hỏi lỗi này là gì và cách sửa XD XD