Error

21:02.30 [Server thread/ERROR] [minecraft/EntityTracker]: "Silently" catching entity tracking error.
net.minecraft.util.ReportedException: Adding entity to track
   at net.minecraft.entity.EntityTracker.track(EntityTracker.java:261) [EntityTracker.class:?]
   at net.minecraft.entity.EntityTracker.track(EntityTracker.java:191) [EntityTracker.class:?]
   at net.minecraft.world.ServerWorldEventHandler.onEntityAdded(ServerWorldEventHandler.java:43) [ServerWorldEventHandler.class:?]
   at net.minecraft.world.World.onEntityAdded(World.java:1326) [World.class:?]
   at net.minecraft.world.WorldServer.onEntityAdded(WorldServer.java:1175) [WorldServer.class:?]
   at net.minecraft.world.World.spawnEntity(World.java:1317) [World.class:?]
   at net.minecraft.world.WorldServer.spawnEntity(WorldServer.java:1121) [WorldServer.class:?]
   at mod.mcreator.mcreator_test$ItemCustom.onItemUse(mcreator_test.java:68) [mcreator_test$ItemCustom.class:?]
   at net.minecraftforge.common.ForgeHooks.onPlaceItemIntoWorld(ForgeHooks.java:876) [ForgeHooks.class:?]
   at net.minecraft.item.ItemStack.onItemUse(ItemStack.java:200) [ItemStack.class:?]
   at net.minecraft.server.management.PlayerInteractionManager.processRightClickBlock(PlayerInteractionManager.java:507) [PlayerInteractionManager.class:?]
   at net.minecraft.network.NetHandlerPlayServer.processTryUseItemOnBlock(NetHandlerPlayServer.java:769) [NetHandlerPlayServer.class:?]
   at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(CPacketPlayerTryUseItemOnBlock.java:68) [CPacketPlayerTryUseItemOnBlock.class:?]
   at net.minecraft.network.play.client.CPacketPlayerTryUseItemOnBlock.processPacket(CPacketPlayerTryUseItemOnBlock.java:13) [CPacketPlayerTryUseItemOnBlock.class:?]
   at net.minecraft.network.PacketThreadUtil$1.run(PacketThreadUtil.java:21) [PacketThreadUtil$1.class:?]
   at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_192]
   at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_192]
   at net.minecraft.util.Util.runTask(Util.java:53) [Util.class:?]
   at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:798) [MinecraftServer.class:?]
   at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:743) [MinecraftServer.class:?]
   at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192) [IntegratedServer.class:?]
   at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:592) [MinecraftServer.class:?]
   at java.lang.Thread.run(Thread.java:748) [?:1.8.0_192]
Caused by: java.lang.IllegalArgumentException: Don't know how to add class mod.mcreator.TestE!
   at net.minecraft.entity.EntityTrackerEntry.createSpawnPacket(EntityTrackerEntry.java:681) ~[EntityTrackerEntry.class:?]
   at net.minecraft.entity.EntityTrackerEntry.updatePlayerEntity(EntityTrackerEntry.java:399) ~[EntityTrackerEntry.class:?]
   at net.minecraft.entity.EntityTrackerEntry.updatePlayerEntities(EntityTrackerEntry.java:509) ~[EntityTrackerEntry.class:?]
   at net.minecraft.entity.EntityTracker.track(EntityTracker.java:235) ~[EntityTracker.class:?]
   ... 22 more