[Events] Task #56 for Events v1.0 generated an exception

java.lang.NullPointerException

at me.skulldev.Main.getRandomPlayers(Main.java:555) ~[?:?]

at me.skulldev.Main$4.run(Main.java:170) ~[?:?]

at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) ~[spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:723) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:374) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:654) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:557) [spigot-1.8.8.jar:git-Spigot-21fe707-e1ebe52]

at java.lang.Thread.run(Thread.java:813) [?:1.8.0_192]