WorldGuard Error

[21:58:44 ERROR]: Could not pass event SpawnEntityEvent to WorldGuard v6.1.2;e38d98d
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:338) ~[JavaPluginLoader$1.class:1.7.10-1614.58]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[RegisteredListener.class:1.7.10-1614.58]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:507) [SimplePluginManager.class:1.7.10-1614.58]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:492) [SimplePluginManager.class:1.7.10-1614.58]
        at com.sk89q.worldguard.bukkit.util.Events.fireAndTestCancel(Events.java:60) [worldguard-6.1.2.jar:?]
        at com.sk89q.worldguard.bukkit.listener.EventAbstractionListener.onEntityDeath(EventAbstractionListener.java:661) [worldguard-6.1.2.jar:?]
        at sun.reflect.GeneratedMethodAccessor298.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_171]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_171]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:334) [JavaPluginLoader$1.class:1.7.10-1614.58]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [RegisteredListener.class:1.7.10-1614.58]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:507) [SimplePluginManager.class:1.7.10-1614.58]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:492) [SimplePluginManager.class:1.7.10-1614.58]
        at org.bukkit.craftbukkit.v1_7_R4.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:360) [CraftEventFactory.class:1.7.10-1614.58]
        at org.bukkit.craftbukkit.v1_7_R4.event.CraftEventFactory.callEntityDeathEvent(CraftEventFactory.java:353) [CraftEventFactory.class:1.7.10-1614.58]
        at net.minecraft.entity.EntityLivingBase.func_70645_a(EntityLivingBase.java:1076) [sv.class:?]
        at net.minecraft.entity.EntityLivingBase.func_70097_a(EntityLivingBase.java:978) [sv.class:?]
        at net.minecraft.entity.monster.EntityMob.func_70097_a(EntityMob.java:71) [yg.class:?]
        at com.brandon3055.draconicevolution.common.items.tools.baseclasses.ToolHandler.damageEntityBasedOnHealth(ToolHandler.java:169) [ToolHandler.class:?]
        at com.brandon3055.draconicevolution.common.items.weapons.WyvernSword.onLeftClickEntity(WyvernSword.java:90) [WyvernSword.class:?]
        at net.minecraft.entity.player.EntityPlayer.func_71059_n(EntityPlayer.java:1357) [yz.class:?]
        at cofh.thermalexpansion.block.device.TileActivator.simLeftClick(TileActivator.java:359) [TileActivator.class:?]
        at cofh.thermalexpansion.block.device.TileActivator.doDeploy(TileActivator.java:188) [TileActivator.class:?]
        at cofh.thermalexpansion.block.device.TileActivator.func_145845_h(TileActivator.java:150) [TileActivator.class:?]
        at net.minecraft.world.World.func_72939_s(World.java:2583) [ahb.class:?]
        at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:673) [mt.class:?]
        at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:986) [MinecraftServer.class:?]
        at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:432) [lt.class:?]
        at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:841) [MinecraftServer.class:?]
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:693) [MinecraftServer.class:?]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_171]
Caused by: java.lang.IllegalArgumentException: Name cannot be null
        at org.apache.commons.lang.Validate.notNull(Validate.java:192) ~[Validate.class:2.6]
        at org.bukkit.craftbukkit.v1_7_R4.CraftServer.getPlayer(CraftServer.java:484) ~[CraftServer.class:1.7.10-1614.58]
        at org.bukkit.Bukkit.getPlayer(Bukkit.java:202) ~[Bukkit.class:1.7.10-1614.58]
        at org.anjocaido.groupmanager.data.User.getBukkitPlayer(User.java:319) ~[?:?]
        at org.anjocaido.groupmanager.permissions.AnjoPermissionsHandler.checkPermission(AnjoPermissionsHandler.java:890) ~[?:?]
        at org.anjocaido.groupmanager.permissions.AnjoPermissionsHandler.checkFullGMPermission(AnjoPermissionsHandler.java:868) ~[?:?]
        at org.anjocaido.groupmanager.permissions.AnjoPermissionsHandler.checkUserPermission(AnjoPermissionsHandler.java:816) ~[?:?]
        at org.anjocaido.groupmanager.permissions.AnjoPermissionsHandler.permission(AnjoPermissionsHandler.java:82) ~[?:?]
        at com.sk89q.wepif.GroupManagerResolver.hasPermission(GroupManagerResolver.java:105) ~[?:?]
        at com.sk89q.wepif.PermissionsResolverManager.hasPermission(PermissionsResolverManager.java:173) ~[?:?]
        at com.sk89q.worldguard.bukkit.WorldGuardPlugin.hasPermission(WorldGuardPlugin.java:476) ~[?:?]
        at com.sk89q.worldguard.bukkit.permission.AbstractPermissionModel.hasPluginPermission(AbstractPermissionModel.java:45) ~[?:?]
        at com.sk89q.worldguard.bukkit.permission.RegionPermissionModel.mayIgnoreRegionProtection(RegionPermissionModel.java:42) ~[?:?]
        at com.sk89q.worldguard.bukkit.listener.RegionProtectionListener.isWhitelisted(RegionProtectionListener.java:140) ~[?:?]
        at com.sk89q.worldguard.bukkit.listener.RegionProtectionListener.onSpawnEntity(RegionProtectionListener.java:321) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor301.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_171]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_171]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:334) ~[JavaPluginLoader$1.class:1.7.10-1614.58]
        ... 30 more