Custom Rendered Block errors

[12:55:50] [Server thread/ERROR] [FML]: A TileEntity type com.wizardofoz.basic.item.entity.TileEntityPurpleGrass has throw an exception trying to write state. It will not persist. Report this to the mod author
java.lang.RuntimeException: class com.wizardofoz.basic.item.entity.TileEntityPurpleGrass is missing a mapping! This is a bug!
	at net.minecraft.tileentity.TileEntity.writeToNBT(TileEntity.java:104) ~[TileEntity.class:?]
	at net.minecraft.world.chunk.storage.AnvilChunkLoader.writeChunkToNBT(AnvilChunkLoader.java:325) [AnvilChunkLoader.class:?]
	at net.minecraft.world.chunk.storage.AnvilChunkLoader.saveChunk(AnvilChunkLoader.java:134) [AnvilChunkLoader.class:?]
	at net.minecraft.world.gen.ChunkProviderServer.safeSaveChunk(ChunkProviderServer.java:229) [ChunkProviderServer.class:?]
	at net.minecraft.world.gen.ChunkProviderServer.saveChunks(ChunkProviderServer.java:281) [ChunkProviderServer.class:?]
	at net.minecraft.world.WorldServer.saveAllChunks(WorldServer.java:883) [WorldServer.class:?]
	at net.minecraft.server.MinecraftServer.saveAllWorlds(MinecraftServer.java:416) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:672) [MinecraftServer.class:?]
	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:120) [IntegratedServer.class:?]
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:528) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:787) [MinecraftServer$2.class:?]
[12:55:50] [Client thread/ERROR]: ########## GL ERROR ##########
[12:55:50] [Client thread/ERROR]: @ Post render
[12:55:50] [Client thread/ERROR]: 1283: Stack overflow
[12:55:50] [Client thread/ERROR]: ########## GL ERROR ##########
[12:55:50] [Client thread/ERROR]: @ Post render
[12:55:50] [Client thread/ERROR]: 1283: Stack overflow
[12:55:50] [Client thread/ERROR]: ########## GL ERROR ##########