Thread.run() has thrown a NullPointerException

We found this prefix in 2 webpages.
MapChildren (2)Typical messages (1)TraceDetailed Map
  1. java.lang.NullPointerException
    1.   at me.gnat008.perworldinventory.data.players.PWIPlayerManager.lambda$scheduleRepeatingTask$0()
    2.   at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftTask.run()
    3.   at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftScheduler.mainThreadHeartbeat()
    4.   at net.minecraft.server.v1_11_R1.MinecraftServer.D()
    5.   at net.minecraft.server.v1_11_R1.DedicatedServer.D()
    6.   at net.minecraft.server.v1_11_R1.MinecraftServer.C()
    7.   at net.minecraft.server.v1_11_R1.MinecraftServer.run()
    8.   at java.lang.Thread.run()
  1. GitHub iconWhat's wrong error..?

    First:1 year ago
    Last:1 year ago
    Author:benefit1337
  2. GitHub iconTask #49 for PerWorldInventory v1.9.0 generated an exception

    First:1 year ago
    Last:1 year ago
    Author:Jocke155
MessageNumber of crashes
<No message>2
  1. java.lang.NullPointerException
    1.   at me.gnat008.perworldinventory.data.players.PWIPlayerManager.lambda$scheduleRepeatingTask$0()
    2.   at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftTask.run()
    3.   at org.bukkit.craftbukkit.v1_11_R1.scheduler.CraftScheduler.mainThreadHeartbeat()
    4.   at net.minecraft.server.v1_11_R1.MinecraftServer.D()
    5.   at net.minecraft.server.v1_11_R1.DedicatedServer.D()
    6.   at net.minecraft.server.v1_11_R1.MinecraftServer.C()
    7.   at net.minecraft.server.v1_11_R1.MinecraftServer.run()
    8.   at java.lang.Thread.run()