pets player quit error

[19:32:57] [Server thread/INFO]: Tirtouga lost connection: Timed out
[19:32:57] [Server thread/ERROR]: Could not pass event PlayerQuitEvent to SimplePets v3.8
org.bukkit.event.EventException: null
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:485) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.PlayerList.disconnect(PlayerList.java:399) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1102) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.PlayerConnection.disconnect(PlayerConnection.java:260) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.PlayerConnection.disconnect(PlayerConnection.java:229) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.PlayerConnection.e(PlayerConnection.java:183) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.NetworkManager.a(NetworkManager.java:233) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.ServerConnection.c(ServerConnection.java:140) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:845) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]
Caused by: java.lang.NullPointerException
	at simplepets.brainsynder.events.OnJoin.onLeave(OnJoin.java:49) ~[SimplePets.jar:?]
	at sun.reflect.GeneratedMethodAccessor697.invoke(Unknown Source) ~[?:?]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
	at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot-1.12.2-R0.1-SNAPSHOT.jar:git-Spigot-d21162c-61e0c69]
	... 15 more
[19:32:57] [Server thread/INFO]: Tirtouga has left Community Brew!