On our server an Enderman managed to place a vanilla grass block on top of a full grown Harvest Festival Grass crop. Whenever a player put that grass block in his crosshairs, the client crashed:
java.lang.NullPointerException: Unexpected error at joshie.harvest.crops.CropHelper.getCropBoundingBox(CropHelper.java:48) at joshie.harvest.crops.block.BlockHFCrops.func_185496_a(BlockHFCrops.java:265) at net.minecraft.block.state.BlockStateContainer$StateImplementation.func_185900_c(BlockStateContainer.java:443) at net.minecraft.block.Block.func_180636_a(Block.java:603) at net.minecraft.block.state.BlockStateContainer$StateImplementation.func_185910_a(BlockStateContainer.java:448) at net.minecraft.world.World.func_147447_a(World.java:1018) at net.minecraft.entity.Entity.func_174822_a(Entity.java:1451) at net.minecraft.client.renderer.EntityRenderer.func_78473_a(EntityRenderer.java:343) at net.minecraft.client.renderer.EntityRenderer.func_78471_a(EntityRenderer.java:1211) at net.minecraft.client.renderer.EntityRenderer.func_181560_a(EntityRenderer.java:1038) at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:1076) at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:371) at net.minecraft.client.main.Main.main(SourceFile:124) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) at net.minecraft.launchwrapper.Launch.main(Launch.java:28) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:310) at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:395) at org.multimc.EntryPoint.listen(EntryPoint.java:170) at org.multimc.EntryPoint.main(EntryPoint.java:54)

The full crash log is here

The crash persisted even when a player broke the grass crop underneath it.
This crash might be related to #57

Ahhhh! Damn enderman breaking things. D=