SpawnMob Error

22:15:39 [SEVERE] Could not pass event ENTITY_TARGET to SpawnMob
java.lang.ClassCastException: org.bukkit.craftbukkit.entity.CraftGhast cannot be cast to org.bukkit.entity.Creature
        at com.jordanneil23.SpawnMob.Friendly.FriendlyMobListener.onEntityTarget(FriendlyMobListener.java:139)
        at org.bukkit.plugin.java.JavaPluginLoader$69.execute(JavaPluginLoader.java:746)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:58)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:339)
        at net.minecraft.server.EntityGhast.m_(EntityGhast.java:107)
        at net.minecraft.server.EntityLiving.d(EntityLiving.java:887)
        at net.minecraft.server.EntityLiving.w_(EntityLiving.java:297)
        at net.minecraft.server.EntityGhast.w_(EntityGhast.java:50)
        at net.minecraft.server.World.entityJoinedWorld(World.java:1253)
        at net.minecraft.server.WorldServer.entityJoinedWorld(WorldServer.java:107)
        at net.minecraft.server.World.playerJoinedWorld(World.java:1235)
        at net.minecraft.server.World.tickEntities(World.java:1142)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:518)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:425)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:457)