[02:47:20 WARN]: [MythicMobs] Task #2457 for MythicMobs v4.5.9-2586 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:141) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[s1.12.2.jar:git-Spigot-7754231-94b0980]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:353) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:739) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_92]
[02:47:20 WARN]: [MythicMobs] Task #2461 for MythicMobs v4.5.9-2586 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:141) ~[?:?]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[s1.12.2.jar:git-Spigot-7754231-94b0980]
        at org.bukkit.craftbukkit.v1_12_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:353) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:739) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [s1.12.2.jar:git-Spigot-7754231-94b0980]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_92]

这里说mod伪装部分空值了，请问你的mod是不是有设置伪装功能如果是的话删除这部分功能看看，如果报错消失，可能是这部分设置有误，或者插件内部问题

是不是没装protocollib