Error log should have gone here

gistfile1.txt

7:01:08] [pool-8-thread-2/INFO]: [Buycraft] Loaded 11 package(s) into the cache.
[17:01:08] [Server thread/ERROR]: Could not pass event PlayerJoinEvent to Factions v0.0.7-b55
org.bukkit.event.EventException
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[spigot.jar:git-Spigot-c136710-350cb99]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot.jar:git-Spigot-c136710-350cb99]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:502) [spigot.jar:git-Spigot-c136710-350cb99]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:487) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.PlayerList.onPlayerJoin(PlayerList.java:296) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.PlayerList.a(PlayerList.java:156) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.LoginListener.b(LoginListener.java:144) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.LoginListener.c(LoginListener.java:54) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.NetworkManager.a(NetworkManager.java:231) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.ServerConnection.c(ServerConnection.java:148) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.MinecraftServer.A(MinecraftServer.java:809) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.DedicatedServer.A(DedicatedServer.java:368) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.MinecraftServer.z(MinecraftServer.java:651) [spigot.jar:git-Spigot-c136710-350cb99]
at net.minecraft.server.v1_8_R2.MinecraftServer.run(MinecraftServer.java:554) [spigot.jar:git-Spigot-c136710-350cb99]
at java.lang.Thread.run(Thread.java:745) [?:1.7.0_75]
Caused by: java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.substring(String.java:1911) ~[?:1.7.0_75]
at com.massivecraft.factions.scoreboards.FTeamWrapper.updatePrefix(FTeamWrapper.java:172) ~[?:?]
at com.massivecraft.factions.scoreboards.FTeamWrapper.add(FTeamWrapper.java:149) ~[?:?]
at com.massivecraft.factions.scoreboards.FTeamWrapper.track(FTeamWrapper.java:116) ~[?:?]
at com.massivecraft.factions.scoreboards.FScoreboard.init(FScoreboard.java:37) ~[?:?]
at com.massivecraft.factions.listeners.FactionsPlayerListener.initPlayer(FactionsPlayerListener.java:75) ~[?:?]
at com.massivecraft.factions.listeners.FactionsPlayerListener.onPlayerJoin(FactionsPlayerListener.java:49) ~[?:?]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.7.0_75]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[?:1.7.0_75]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.7.0_75]
at java.lang.reflect.Method.invoke(Method.java:606) ~[?:1.7.0_75]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:301) ~[spigot.jar:git-Spigot-c136710-350cb99]
... 14 more