Crash when using my automatic tree farm

I turned on my automatic tree farm in the new snapshot, and after a few pistons moving about, my world crashes with Description: Ticking entity.

It happens every time i use the farm. I'm not sure if it happens to you, since your farm is probably different than mine. It should be said that i haven't played this world since 1.9. here's a log of the crash:

---- Minecraft Crash Report ----
// I let you down. Sorry :(

Time: 06-10-16 21:53
Description: Ticking block entity

java.lang.IllegalArgumentException: Cannot get property att{name=facing, clazz=class cv, values=[down, up, north, south, west, east]} as it does not exist in ath{block=minecraft:air, properties=[]}
	at ath$a.c(SourceFile:166)
	at ata.j(SourceFile:102)
	at ata.a(SourceFile:92)
	at ata.f(SourceFile:110)
	at ata.F_(SourceFile:233)
	at ajn.k(SourceFile:1429)
	at ben.t(SourceFile:1649)
	at ben.av(SourceFile:967)
	at ben.a(SourceFile:395)
	at net.minecraft.client.main.Main.main(SourceFile:124)


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

-- Head --
Thread: Client thread
Stacktrace:
	at ath$a.c(SourceFile:166)
	at ata.j(SourceFile:102)
	at ata.a(SourceFile:92)
	at ata.f(SourceFile:110)
	at ata.F_(SourceFile:233)

-- Block entity being ticked --
Details:
	Name: minecraft:piston // ata
	Block type: ID #36 (tile.null // asz)
	Block data value: 0 / 0x0 / 0b0000
	Block location: World: (-395,6,-2172), Chunk: (at 5,0,4 in -25,-136; contains blocks -400,0,-2176 to -385,255,-2161), Region: (-1,-5; contains chunks -32,-160 to -1,-129, blocks -512,0,-2560 to -1,255,-2049)
	Actual block type: ID #36 (tile.null // asz)
	Actual block data value: 13 / 0xD / 0b1101
Stacktrace:
	at ajn.k(SourceFile:1429)

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bpn['TheCaveExplorer'/623, l='MpServer', x=-385,76, y=3,00, z=-2171,82]]
	Chunk stats: MultiplayerChunkCache: 289, 289
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (-463,4,-1982), Chunk: (at 1,0,2 in -29,-124; contains blocks -464,0,-1984 to -449,255,-1969), Region: (-1,-4; contains chunks -32,-128 to -1,-97, blocks -512,0,-2048 to -1,255,-1537)
	Level time: 10279423 game time, 13425395 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 155 total; [aca['entity.MinecartRideable.name'/265, l='MpServer', x=-383,51, y=5,06, z=-2100,50], aap['Villager'/266, l='MpServer', x=-352,29, y=17,08, z=-2144,32], aap['Villager'/267, l='MpServer', x=-352,77, y=87,15, z=-2144,28], aap['Villager'/268, l='MpServer', x=-352,10, y=87,35, z=-2145,08], aap['Villager'/269, l='MpServer', x=-352,78, y=17,15, z=-2143,65], aap['Villager'/270, l='MpServer', x=-352,15, y=17,38, z=-2143,61], aap['Villager'/271, l='MpServer', x=-352,28, y=87,24, z=-2143,63], aca['entity.MinecartRideable.name'/272, l='MpServer', x=-360,50, y=5,06, z=-2110,19], aad['Slime'/273, l='MpServer', x=-353,86, y=3,52, z=-2106,97], aap['Villager'/279, l='MpServer', x=-360,70, y=4,00, z=-2093,50], aap['Villager'/286, l='MpServer', x=-340,38, y=17,32, z=-2157,13], aap['Villager'/287, l='MpServer', x=-340,33, y=17,32, z=-2155,61], aap['Villager'/288, l='MpServer', x=-339,62, y=17,24, z=-2155,59], aap['Villager'/289, l='MpServer', x=-339,57, y=17,55, z=-2156,23], aap['Villager'/290, l='MpServer', x=-340,35, y=17,21, z=-2156,29], wu['Cow'/546, l='MpServer', x=-319,97, y=2,00, z=-2095,45], aap['Villager'/293, l='MpServer', x=-340,34, y=87,01, z=-2155,68], aap['Villager'/294, l='MpServer', x=-340,32, y=87,13, z=-2156,32], aap['Villager'/295, l='MpServer', x=-339,67, y=87,61, z=-2156,29], aap['Villager'/296, l='MpServer', x=-339,66, y=87,32, z=-2155,62], aap['Villager'/297, l='MpServer', x=-351,90, y=87,14, z=-2144,27], aap['Villager'/298, l='MpServer', x=-340,30, y=17,15, z=-2131,69], aap['Villager'/299, l='MpServer', x=-339,63, y=17,53, z=-2132,34], aap['Villager'/300, l='MpServer', x=-340,30, y=17,51, z=-2132,29], aap['Villager'/301, l='MpServer', x=-339,68, y=17,10, z=-2131,63], aap['Villager'/303, l='MpServer', x=-338,96, y=87,25, z=-2131,61], aap['Villager'/304, l='MpServer', x=-339,75, y=87,21, z=-2132,56], aap['Villager'/305, l='MpServer', x=-340,36, y=87,08, z=-2132,37], aap['Villager'/306, l='MpServer', x=-339,69, y=87,19, z=-2131,56], aap['Villager'/307, l='MpServer', x=-340,30, y=87,45, z=-2131,73], yv['entity.ItemFrame.name'/564, l='MpServer', x=-291,97, y=4,50, z=-2100,50], yv['entity.ItemFrame.name'/565, l='MpServer', x=-291,97, y=4,50, z=-2096,50], abz['Minecart with Hopper'/310, l='MpServer', x=-343,51, y=5,00, z=-2105,51], yv['entity.ItemFrame.name'/566, l='MpServer', x=-291,97, y=4,50, z=-2098,50], abz['Minecart with Hopper'/311, l='MpServer', x=-343,49, y=5,00, z=-2105,51], yv['entity.ItemFrame.name'/567, l='MpServer', x=-291,97, y=4,50, z=-2087,50], wt['Chicken'/312, l='MpServer', x=-343,80, y=8,06, z=-2105,80], yv['entity.ItemFrame.name'/568, l='MpServer', x=-291,97, y=4,50, z=-2085,50], wt['Chicken'/313, l='MpServer', x=-343,20, y=8,06, z=-2105,20], yv['entity.ItemFrame.name'/569, l='MpServer', x=-291,97, y=4,50, z=-2089,50], wt['Chicken'/314, l='MpServer', x=-343,80, y=8,06, z=-2105,20], wt['Chicken'/315, l='MpServer', x=-343,20, y=8,06, z=-2105,80], wt['Chicken'/316, l='MpServer', x=-343,78, y=5,31, z=-2105,23], yx['Painting'/317, l='MpServer', x=-348,97, y=1,50, z=-2093,00], yv['entity.ItemFrame.name'/319, l='MpServer', x=-347,50, y=2,50, z=-2091,03], yv['entity.ItemFrame.name'/575, l='MpServer', x=-287,03, y=4,50, z=-2096,50], yx['Painting'/320, l='MpServer', x=-348,97, y=2,50, z=-2093,00], yv['entity.ItemFrame.name'/576, l='MpServer', x=-287,03, y=4,50, z=-2100,50], yv['entity.ItemFrame.name'/577, l='MpServer', x=-287,03, y=4,50, z=-2098,50], yv['entity.ItemFrame.name'/581, l='MpServer', x=-287,03, y=4,50, z=-2089,50], yv['entity.ItemFrame.name'/582, l='MpServer', x=-287,03, y=4,50, z=-2087,50], yv['entity.ItemFrame.name'/583, l='MpServer', x=-287,03, y=4,50, z=-2085,50], aap['Villager'/332, l='MpServer', x=-327,57, y=17,11, z=-2144,39], aap['Villager'/333, l='MpServer', x=-328,30, y=17,17, z=-2144,36], aap['Villager'/334, l='MpServer', x=-327,71, y=87,32, z=-2144,38], aap['Villager'/335, l='MpServer', x=-328,35, y=87,03, z=-2144,37], aap['Villager'/336, l='MpServer', x=-327,69, y=17,55, z=-2143,74], aap['Villager'/337, l='MpServer', x=-328,30, y=17,35, z=-2143,70], aap['Villager'/338, l='MpServer', x=-327,68, y=87,42, z=-2143,58], aap['Villager'/339, l='MpServer', x=-328,33, y=87,33, z=-2143,71], yx['Painting'/317, l='MpServer', x=-348,97, y=1,50, z=-2093,00], xa['Rabbit'/340, l='MpServer', x=-325,71, y=2,00, z=-2107,77], xa['Rabbit'/341, l='MpServer', x=-324,20, y=2,00, z=-2106,42], yx['Painting'/320, l='MpServer', x=-348,97, y=2,50, z=-2093,00], wy['Pig'/342, l='MpServer', x=-322,28, y=2,00, z=-2105,45], wy['Pig'/343, l='MpServer', x=-320,45, y=2,00, z=-2107,59], wy['Pig'/344, l='MpServer', x=-322,55, y=2,00, z=-2108,55], xa['Rabbit'/345, l='MpServer', x=-324,76, y=2,00, z=-2107,97], xa['Rabbit'/346, l='MpServer', x=-324,81, y=2,00, z=-2108,80], xa['Rabbit'/347, l='MpServer', x=-326,22, y=2,00, z=-2106,61], xa['Rabbit'/348, l='MpServer', x=-326,80, y=2,00, z=-2106,72], wy['Pig'/349, l='MpServer', x=-322,38, y=2,00, z=-2107,64], xa['Rabbit'/350, l='MpServer', x=-326,27, y=2,00, z=-2107,24], wy['Pig'/351, l='MpServer', x=-321,34, y=2,00, z=-2105,45], xa['Rabbit'/352, l='MpServer', x=-325,89, y=2,00, z=-2108,36], xa['Rabbit'/353, l='MpServer', x=-325,53, y=2,00, z=-2105,71], xa['Rabbit'/354, l='MpServer', x=-325,54, y=2,00, z=-2107,24], xa['Rabbit'/355, l='MpServer', x=-326,29, y=2,00, z=-2108,80], xa['Rabbit'/356, l='MpServer', x=-326,67, y=2,13, z=-2107,14], wy['Pig'/357, l='MpServer', x=-321,43, y=2,00, z=-2107,54], wt['Chicken'/358, l='MpServer', x=-320,20, y=2,00, z=-2105,20], wy['Pig'/359, l='MpServer', x=-320,45, y=2,00, z=-2106,27], wy['Pig'/360, l='MpServer', x=-320,45, y=2,00, z=-2108,55], xa['Rabbit'/361, l='MpServer', x=-324,20, y=2,00, z=-2105,60], wy['Pig'/362, l='MpServer', x=-322,55, y=2,00, z=-2106,35], wy['Pig'/363, l='MpServer', x=-321,55, y=2,00, z=-2106,51], xa['Rabbit'/364, l='MpServer', x=-324,20, y=2,00, z=-2108,52], xa['Rabbit'/365, l='MpServer', x=-325,13, y=2,00, z=-2106,81], wy['Pig'/366, l='MpServer', x=-321,45, y=2,00, z=-2108,55], wu['Cow'/367, l='MpServer', x=-320,63, y=2,00, z=-2096,80], xb['Sheep'/625, l='MpServer', x=-344,10, y=4,49, z=-2216,27], zf['item.tile.sapling.oak'/1906, l='MpServer', x=-391,28, y=7,63, z=-2173,86], aap['Villager'/144, l='MpServer', x=-465,30, y=4,00, z=-2133,59], aap['Villager'/150, l='MpServer', x=-465,60, y=4,00, z=-2139,99], aap['Villager'/156, l='MpServer', x=-465,30, y=4,00, z=-2134,27], wu['Cow'/416, l='MpServer', x=-323,32, y=2,00, z=-2095,49], wu['Cow'/418, l='MpServer', x=-326,10, y=2,00, z=-2095,63], zf['item.tile.sapling.oak'/1956, l='MpServer', x=-393,13, y=9,88, z=-2171,15], aap['Villager'/171, l='MpServer', x=-465,30, y=4,00, z=-2135,03], aap['Villager'/180, l='MpServer', x=-465,30, y=4,00, z=-2138,12], yv['entity.ItemFrame.name'/438, l='MpServer', x=-313,50, y=1,50, z=-2097,03], yv['entity.ItemFrame.name'/439, l='MpServer', x=-309,03, y=3,50, z=-2100,50], yv['entity.ItemFrame.name'/440, l='MpServer', x=-309,03, y=3,50, z=-2098,50], wt['Chicken'/441, l='MpServer', x=-318,80, y=2,00, z=-2106,05], yv['entity.ItemFrame.name'/442, l='MpServer', x=-309,03, y=2,50, z=-2100,50], yv['entity.ItemFrame.name'/443, l='MpServer', x=-309,03, y=2,50, z=-2106,50], yv['entity.ItemFrame.name'/444, l='MpServer', x=-309,03, y=3,50, z=-2102,50], yv['entity.ItemFrame.name'/445, l='MpServer', x=-311,50, y=2,50, z=-2097,03], yv['entity.ItemFrame.name'/446, l='MpServer', x=-309,03, y=1,50, z=-2104,50], wt['Chicken'/447, l='MpServer', x=-316,20, y=2,00, z=-2108,24], yv['entity.ItemFrame.name'/448, l='MpServer', x=-310,50, y=1,50, z=-2106,97], wt['Chicken'/449, l='MpServer', x=-317,18, y=2,00, z=-2108,19], aap['Villager'/194, l='MpServer', x=-465,30, y=4,00, z=-2136,80], yv['entity.ItemFrame.name'/450, l='MpServer', x=-309,03, y=1,50, z=-2100,50], yv['entity.ItemFrame.name'/451, l='MpServer', x=-312,50, y=3,50, z=-2106,97], yv['entity.ItemFrame.name'/452, l='MpServer', x=-309,03, y=2,50, z=-2098,50], yv['entity.ItemFrame.name'/453, l='MpServer', x=-309,03, y=3,50, z=-2104,50], wt['Chicken'/454, l='MpServer', x=-317,22, y=2,00, z=-2105,20], yv['entity.ItemFrame.name'/455, l='MpServer', x=-309,03, y=1,50, z=-2098,50], wt['Chicken'/456, l='MpServer', x=-316,23, y=2,00, z=-2107,67], aap['Villager'/201, l='MpServer', x=-465,50, y=4,00, z=-2141,59], yv['entity.ItemFrame.name'/457, l='MpServer', x=-309,50, y=3,50, z=-2097,03], yv['entity.ItemFrame.name'/458, l='MpServer', x=-312,50, y=1,50, z=-2106,97], wt['Chicken'/459, l='MpServer', x=-317,78, y=2,00, z=-2108,78], yv['entity.ItemFrame.name'/460, l='MpServer', x=-309,50, y=1,50, z=-2097,03], yv['entity.ItemFrame.name'/461, l='MpServer', x=-312,50, y=2,50, z=-2106,97], wt['Chicken'/462, l='MpServer', x=-316,74, y=2,00, z=-2108,64], yv['entity.ItemFrame.name'/463, l='MpServer', x=-313,50, y=2,50, z=-2097,03], yv['entity.ItemFrame.name'/464, l='MpServer', x=-309,03, y=1,50, z=-2106,50], yv['entity.ItemFrame.name'/465, l='MpServer', x=-310,50, y=2,50, z=-2106,97], yv['entity.ItemFrame.name'/466, l='MpServer', x=-313,50, y=3,50, z=-2097,03], yv['entity.ItemFrame.name'/467, l='MpServer', x=-309,03, y=3,50, z=-2106,50], yv['entity.ItemFrame.name'/468, l='MpServer', x=-309,03, y=2,50, z=-2104,50], yv['entity.ItemFrame.name'/469, l='MpServer', x=-309,50, y=2,50, z=-2097,03], yv['entity.ItemFrame.name'/470, l='MpServer', x=-309,03, y=2,50, z=-2102,50], yv['entity.ItemFrame.name'/471, l='MpServer', x=-311,50, y=3,50, z=-2097,03], wt['Chicken'/472, l='MpServer', x=-318,03, y=2,00, z=-2105,22], yv['entity.ItemFrame.name'/473, l='MpServer', x=-309,03, y=1,50, z=-2102,50], wt['Chicken'/474, l='MpServer', x=-318,57, y=2,00, z=-2107,51], wt['Chicken'/475, l='MpServer', x=-316,20, y=2,00, z=-2108,80], wt['Chicken'/476, l='MpServer', x=-318,06, y=2,00, z=-2105,67], wt['Chicken'/477, l='MpServer', x=-318,17, y=2,00, z=-2108,34], yv['entity.ItemFrame.name'/478, l='MpServer', x=-311,50, y=1,50, z=-2097,03], wt['Chicken'/479, l='MpServer', x=-318,09, y=2,00, z=-2106,60], wt['Chicken'/480, l='MpServer', x=-318,38, y=2,00, z=-2106,12], yv['entity.ItemFrame.name'/481, l='MpServer', x=-310,50, y=3,50, z=-2106,97], wu['Cow'/482, l='MpServer', x=-316,64, y=2,00, z=-2096,75], wu['Cow'/486, l='MpServer', x=-316,64, y=2,00, z=-2098,55], wu['Cow'/487, l='MpServer', x=-318,56, y=2,00, z=-2097,61], bpn['TheCaveExplorer'/623, l='MpServer', x=-385,76, y=3,00, z=-2171,82], wu['Cow'/488, l='MpServer', x=-317,64, y=2,00, z=-2096,54], wu['Cow'/489, l='MpServer', x=-317,60, y=2,00, z=-2097,52], wu['Cow'/490, l='MpServer', x=-318,60, y=2,00, z=-2096,50], wu['Cow'/494, l='MpServer', x=-317,81, y=2,00, z=-2098,53], yt['Armor Stand'/239, l='MpServer', x=-450,50, y=2,00, z=-2113,50]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Integrated singleplayer server
Stacktrace:
	at bnl.a(SourceFile:365)
	at ben.b(SourceFile:2536)
	at ben.a(SourceFile:404)
	at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
	Minecraft Version: 16w40a
	Operating System: Windows 8.1 (amd64) version 6.3
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 160440152 bytes (153 MB) / 310509568 bytes (296 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: 16w40a
	LWJGL: 2.9.4
	OpenGL: GeForce GT 745M/PCIe/SSE2 GL version 4.5.0 NVIDIA 358.91, NVIDIA Corporation
	GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

	Using VBOs: Yes
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: 
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	CPU: 8x Intel(R) Core(TM) i7-4700MQ CPU @ 2.40GHz