Every time a player stands on a pressure plate this error is thrown:
Could not pass event PlayerInteractEvent to PreciousStones v10.3.0 org.bukkit.event.EventException at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:310) ~[spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at org.bukkit.craftbukkit.v1_9_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:231) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at org.bukkit.craftbukkit.v1_9_R1.event.CraftEventFactory.callPlayerInteractEvent(CraftEventFactory.java:198) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.BlockPressurePlateBinary.e(BlockPressurePlateBinary.java:75) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.BlockPressurePlateAbstract.a(BlockPressurePlateAbstract.java:94) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.BlockPressurePlateAbstract.a(BlockPressurePlateAbstract.java:87) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.Entity.checkBlockCollisions(Entity.java:839) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.Entity.move(Entity.java:473) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityLiving.g(EntityLiving.java:1644) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityHuman.g(EntityHuman.java:1436) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityLiving.n(EntityLiving.java:1946) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityHuman.n(EntityHuman.java:339) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityLiving.m(EntityLiving.java:1775) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityHuman.m(EntityHuman.java:142) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.EntityPlayer.k_(EntityPlayer.java:239) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.PlayerConnection.c(PlayerConnection.java:139) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.NetworkManager.a(NetworkManager.java:232) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.ServerConnection.c(ServerConnection.java:141) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.MinecraftServer.D(MinecraftServer.java:820) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.DedicatedServer.D(DedicatedServer.java:400) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.MinecraftServer.C(MinecraftServer.java:660) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at net.minecraft.server.v1_9_R1.MinecraftServer.run(MinecraftServer.java:559) [spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] at java.lang.Thread.run(Unknown Source) [?:1.8.0_91] Caused by: java.lang.NullPointerException at net.sacredlabyrinth.Phaed.PreciousStones.listeners.PSPlayerListener.onPlayerInteract(PSPlayerListener.java:522) ~[?:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_91] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_91] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_91] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_91] at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.9.2.jar:git-Spigot-e000104-4cb3258] ... 25 more

Thanks for your time.

(Error also attached here as txt for readability
ps error2.txt)