When we updated from .172 to .179 we thought it was the bore lens causing the crash, but after disabling the 'automatic livingrock farm' the player re-assembled it just to generate the livingrock (by pushing stone near a pure daisy), and it caused another crash as soon as it pushed the stone. I'm not sure what all you need, so I've included the crash log except system specs and modlist.

---- Minecraft Crash Report ----
// There are four lights!

Time: 4/18/15 8:57 AM
Description: Ticking block entity

java.lang.NullPointerException: Ticking block entity
at net.minecraft.item.ItemStack.func_77960_j(ItemStack.java:217)
at vazkii.botania.api.recipe.RecipePureDaisy.isOreDict(RecipePureDaisy.java:52)
at vazkii.botania.api.recipe.RecipePureDaisy.matches(RecipePureDaisy.java:45)
at vazkii.botania.common.block.subtile.SubTilePureDaisy.onUpdate(SubTilePureDaisy.java:60)
at vazkii.botania.common.block.tile.TileSpecialFlower.func_145845_h(TileSpecialFlower.java:92)
at net.minecraft.world.World.func_72939_s(World.java:1939)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:636)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Stacktrace:
at net.minecraft.item.ItemStack.func_77960_j(ItemStack.java:217)
at vazkii.botania.api.recipe.RecipePureDaisy.isOreDict(RecipePureDaisy.java:52)
at vazkii.botania.api.recipe.RecipePureDaisy.matches(RecipePureDaisy.java:45)
at vazkii.botania.common.block.subtile.SubTilePureDaisy.onUpdate(SubTilePureDaisy.java:60)
at vazkii.botania.common.block.tile.TileSpecialFlower.func_145845_h(TileSpecialFlower.java:92)

-- Block entity being ticked --
Details:
Name: botania:specialFlower // vazkii.botania.common.block.tile.TileSpecialFlower
Block type: ID #498 (tile.specialFlower // vazkii.botania.common.block.BlockSpecialFlower)
Block data value: 0 / 0x0 / 0b0000
Block location: World: (-291,70,161), Chunk: (at 13,4,1 in -19,10; contains blocks -304,0,160 to -289,255,175), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Actual block type: ID #498 (tile.specialFlower // vazkii.botania.common.block.BlockSpecialFlower)
Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:1939)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489)

-- Affected level --
Details:
Level name: Reckless
All players: 0 total; []
Chunk stats: ServerChunkCache: 635 Drop: 0
Level seed: -1359059433
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: World: (-216,64,196), Chunk: (at 8,4,4 in -14,12; contains blocks -224,0,192 to -209,255,207), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 40600945 game time, 10624 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 10971 (now: false), thunder time: 77101 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:636)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)

Apologies, we were on .171 and updated to .179, not .172.

I can't reproduce this, do you have cauldron?

Ok, I found out the issue. It never happens in vanilla so I can't reproduce it, but under some circumstances it can break, so I'll patch it.