Silently catching

[SEVERE] "Silently" catching entity tracking error.
2014-05-11 14:25:29 [SEVERE] net.minecraft.util.ReportedException: Adding entity to track
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72785_a(EntityTracker.java:226)
2014-05-11 14:25:29 [SEVERE]    at cpw.mods.fml.common.registry.EntityRegistry.tryTrackingEntity(EntityRegistry.java:400)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72786_a(EntityTracker.java:64)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.WorldManager.func_72703_a(WorldManager.java:37)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.func_72923_a(World.java:2026)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.WorldServer.func_72923_a(WorldServer.java:1292)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.addEntity(World.java:2016)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.func_72838_d(World.java:1911)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.management.ServerConfigurationManager.repositionEntity(ServerConfigurationManager.java:1084)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.Entity.teleportTo(Entity.java:2869)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.Entity.func_71027_c(Entity.java:2849)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.Entity.func_70030_z(Entity.java:585)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityLivingBase.func_70030_z(EntityLivingBase.java:286)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityLiving.func_70030_z(EntityLiving.java:206)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity7HasAI.func_70030_z(Entity7HasAI.java:91)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.Entity.func_70071_h_(Entity.java:537)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityLivingBase.func_70071_h_(EntityLivingBase.java:1928)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityLiving.func_70071_h_(EntityLiving.java:264)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity1Base.func_70071_h_(Entity1Base.java:138)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity2HasModel.func_70071_h_(Entity2HasModel.java:134)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity3HasStats.func_70071_h_(Entity3HasStats.java:301)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity4Textures.func_70071_h_(Entity4Textures.java:120)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity5Rideable.func_70071_h_(Entity5Rideable.java:448)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.Entity8HoldsItems.func_70071_h_(Entity8HoldsItems.java:51)
2014-05-11 14:25:29 [SEVERE]    at pixelmon.entities.pixelmon.EntityPixelmon.func_70071_h_(EntityPixelmon.java:205)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.func_72866_a(World.java:2944)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.WorldServer.func_72866_a(WorldServer.java:1006)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.func_72870_g(World.java:2890)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.world.World.func_72939_s(World.java:2704)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:883)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:330)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:777)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:659)
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)
2014-05-11 14:25:29 [SEVERE] Caused by: java.lang.IllegalStateException: Entity is already tracked!
2014-05-11 14:25:29 [SEVERE]    at net.minecraft.entity.EntityTracker.func_72785_a(EntityTracker.java:206)
2014-05-11 14:25:29 [SEVERE]    ... 33 more
2014-05-11 14:25:30