Minecraft crashes when i try to place a sapling.
Crash report:

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 2015.12.02. 19:54
Description: Unexpected error

java.lang.NullPointerException: Unexpected error
at rx.a_(SourceFile:409)
at zo.a(SourceFile:1818)
at rx.a(SourceFile:1198)
at bbz.au(SourceFile:1435)
at bbz.ax(SourceFile:1934)
at bbz.aw(SourceFile:1752)
at bbz.s(SourceFile:1596)
at bbz.as(SourceFile:942)
at bbz.a(SourceFile:386)
at net.minecraft.client.main.Main.main(SourceFile:122)

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

– Head –
Stacktrace:
at rx.a_(SourceFile:409)
at zo.a(SourceFile:1818)
at rx.a(SourceFile:1198)
at bbz.au(SourceFile:1435)
at bbz.ax(SourceFile:1934)
at bbz.aw(SourceFile:1752)

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bmg['Asztro2'/176, l='MpServer', x=-182,54, y=64,00, z=252,51]]
Chunk stats: MultiplayerChunkCache: 361, 361
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (-44,64,248), Chunk: (at 4,4,8 in -3,15; contains blocks -48,0,240 to -33,255,255), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 1416721 game time, 1949148 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: 69 total; [zf['Zombi'/256, l='MpServer', x=-253,50, y=12,00, z=277,50], vz['Nyúl'/257, l='MpServer', x=-246,50, y=94,00, z=278,59], vz['Nyúl'/258, l='MpServer', x=-253,59, y=93,00, z=288,06], yn['Creeper'/774, l='MpServer', x=-240,50, y=34,00, z=296,50], yn['Creeper'/775, l='MpServer', x=-238,50, y=34,00, z=296,50], vz['Nyúl'/8, l='MpServer', x=-225,66, y=63,00, z=188,09], vz['Nyúl'/9, l='MpServer', x=-235,63, y=67,00, z=203,19], vz['Nyúl'/10, l='MpServer', x=-227,88, y=64,00, z=198,91], vz['Nyúl'/11, l='MpServer', x=-237,09, y=70,00, z=201,44], zf['Zombi'/12, l='MpServer', x=-226,50, y=38,00, z=253,50], xz['item.item.rottenFlesh'/14, l='MpServer', x=-237,69, y=91,00, z=271,03], vz['Nyúl'/15, l='MpServer', x=-224,50, y=70,00, z=278,66], vt['Csirke'/16, l='MpServer', x=-229,59, y=69,00, z=323,56], xz['item.item.egg'/659, l='MpServer', x=-175,66, y=63,00, z=224,84], xz['item.item.rottenFlesh'/34, l='MpServer', x=-205,13, y=64,00, z=301,53], vz['Nyúl'/42, l='MpServer', x=-180,03, y=78,00, z=198,34], vt['Csirke'/43, l='MpServer', x=-176,28, y=63,00, z=225,50], vu['Tehén'/44, l='MpServer', x=-177,22, y=63,00, z=230,72], vt['Csirke'/45, l='MpServer', x=-170,78, y=63,00, z=225,72], xz['item.item.egg'/46, l='MpServer', x=-177,94, y=63,00, z=224,75], vq['Denevér'/814, l='MpServer', x=-118,27, y=37,00, z=191,60], xo['entity.LeashKnot.name'/175, l='MpServer', x=-158,50, y=63,50, z=234,50], vq['Denevér'/815, l='MpServer', x=-118,56, y=37,85, z=190,48], vy['Malac'/57, l='MpServer', x=-170,09, y=63,00, z=225,84], wa['Bárány'/58, l='MpServer', x=-170,09, y=63,00, z=226,91], xz['item.item.egg'/59, l='MpServer', x=-169,75, y=63,00, z=224,81], vy['Malac'/60, l='MpServer', x=-172,22, y=63,00, z=225,06], xz['item.item.egg'/316, l='MpServer', x=-177,69, y=63,00, z=230,59], vu['Tehén'/61, l='MpServer', x=-173,34, y=63,00, z=225,06], vy['Malac'/62, l='MpServer', x=-173,38, y=63,00, z=228,38], wa['Bárány'/63, l='MpServer', x=-178,50, y=63,00, z=227,16], vt['Csirke'/64, l='MpServer', x=-169,84, y=63,00, z=228,66], vy['Malac'/65, l='MpServer', x=-172,81, y=63,00, z=230,94], vt['Csirke'/66, l='MpServer', x=-169,84, y=63,00, z=224,81], wa['Bárány'/67, l='MpServer', x=-171,16, y=63,00, z=226,47], xn['entity.ItemFrame.name'/68, l='MpServer', x=-168,97, y=69,50, z=242,50], xn['entity.ItemFrame.name'/69, l='MpServer', x=-168,97, y=68,50, z=242,50], xn['entity.ItemFrame.name'/70, l='MpServer', x=-168,97, y=68,50, z=241,50], xn['entity.ItemFrame.name'/71, l='MpServer', x=-168,97, y=69,50, z=243,50], xn['entity.ItemFrame.name'/72, l='MpServer', x=-168,97, y=70,50, z=243,50], xn['entity.ItemFrame.name'/73, l='MpServer', x=-168,97, y=70,50, z=242,50], xn['entity.ItemFrame.name'/74, l='MpServer', x=-168,97, y=69,50, z=244,50], xn['entity.ItemFrame.name'/75, l='MpServer', x=-168,97, y=68,50, z=243,50], xn['entity.ItemFrame.name'/76, l='MpServer', x=-168,97, y=70,50, z=241,50], xn['entity.ItemFrame.name'/77, l='MpServer', x=-168,97, y=69,50, z=245,50], xl['Páncélállvány'/78, l='MpServer', x=-162,50, y=68,00, z=245,50], bmg['Asztro2'/176, l='MpServer', x=-182,54, y=64,00, z=252,51], xn['entity.ItemFrame.name'/79, l='MpServer', x=-168,97, y=70,50, z=245,50], xn['entity.ItemFrame.name'/80, l='MpServer', x=-168,97, y=70,50, z=244,50], xn['entity.ItemFrame.name'/81, l='MpServer', x=-168,97, y=69,50, z=241,50], xn['entity.ItemFrame.name'/82, l='MpServer', x=-168,97, y=69,50, z=249,50], xn['entity.ItemFrame.name'/83, l='MpServer', x=-162,03, y=69,50, z=247,50], wg['Ló'/91, l='MpServer', x=-159,41, y=63,00, z=233,09], xz['item.item.rottenFlesh'/92, l='MpServer', x=-150,09, y=64,00, z=285,00], xz['item.item.rottenFlesh'/93, l='MpServer', x=-146,28, y=66,00, z=289,97], vz['Nyúl'/101, l='MpServer', x=-132,97, y=72,00, z=179,53], zf['Zombi'/102, l='MpServer', x=-133,50, y=50,00, z=204,06], zd['Pók'/103, l='MpServer', x=-139,50, y=23,00, z=216,50], zb['Csontváz'/104, l='MpServer', x=-140,50, y=19,00, z=326,50], vy['Malac'/105, l='MpServer', x=-138,56, y=64,00, z=332,84], vq['Denevér'/751, l='MpServer', x=-113,25, y=18,94, z=210,25], zf['Zombi'/112, l='MpServer', x=-125,97, y=45,00, z=196,34], vq['Denevér'/113, l='MpServer', x=-108,53, y=17,97, z=215,44], vz['Nyúl'/245, l='MpServer', x=-262,56, y=94,00, z=232,50], vz['Nyúl'/247, l='MpServer', x=-259,50, y=94,00, z=232,19], vz['Nyúl'/251, l='MpServer', x=-246,53, y=71,00, z=207,34], vz['Nyúl'/252, l='MpServer', x=-249,50, y=93,00, z=242,28], vz['Nyúl'/253, l='MpServer', x=-253,81, y=91,00, z=247,53], zf['Zombi'/255, l='MpServer', x=-252,50, y=12,00, z=280,50]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bkh.a(SourceFile:364)
at bbz.b(SourceFile:2496)
at bbz.a(SourceFile:400)
at net.minecraft.client.main.Main.main(SourceFile:122)

– System Details –
Details:
Minecraft Version: 15w49a
Operating System: Windows 10 (x86) version 10.0
Java Version: 1.8.0_65, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 136726248 bytes (130 MB) / 320544768 bytes (305 MB) up to 523501568 bytes (499 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
Launched Version: 15w49a
LWJGL: 2.9.4
OpenGL: ATI Mobility Radeon HD 3400 Series GL version 3.3.11672 Compatibility Profile Context, ATI Technologies Inc.
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: Faithful 32x32 15w44b
Current Language: Magyar (Magyarország)
Profiler Position: N/A (disabled)
CPU: 2x Intel(R) Core(TM)2 Duo CPU T5750 @ 2.00GHz