So I'm just gonna get straight to the point, everything was working fine until I tried to smelt some Iron then minecraft crashed so I got back on and tried again, and it crashed again i noticed that it crashed when i put the coal in the furnace so how to get the glitch is simple
1. make a furnace
2. put stuff in the top of the furnace
3. put coal in the bottom of the furnace

and then minecraft crashes here is the crash report i get
---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 9/28/16 1:52 PM
Description: Updating screen events

java.lang.NullPointerException: Updating screen events
at asg.b(SourceFile:316)
at asg.c(SourceFile:372)
at acr.a(SourceFile:15)
at acg.a(SourceFile:218)
at bni.a(SourceFile:413)
at bhz.a(SourceFile:512)
at bhz.b(SourceFile:483)
at bhh.k(SourceFile:409)
at bhh.p(SourceFile:380)
at bel.t(SourceFile:1583)
at bel.av(SourceFile:967)
at bel.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 asg.b(SourceFile:316)
at asg.c(SourceFile:372)
at acr.a(SourceFile:15)
at acg.a(SourceFile:218)
at bni.a(SourceFile:413)
at bhz.a(SourceFile:512)
at bhz.b(SourceFile:483)
at bhh.k(SourceFile:409)
at bhh.p(SourceFile:380)

– Affected screen –
Details:
Screen name: bin

– Affected level –
Details:
Level name: MpServer
All players: 1 total; [bpl['Jsrgaming123'/335, l='MpServer', x=-49.38, y=71.00, z=270.50]]
Chunk stats: MultiplayerChunkCache: 624, 624
Level seed: 0
Level generator: ID 00 - default, ver 1. Features enabled: false
Level generator options:
Level spawn location: World: (-64,64,256), Chunk: (at 0,4,0 in -4,16; contains blocks -64,0,256 to -49,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 62527 game time, 62527 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: 111 total; [ws['Cow'/256, l='MpServer', x=26.47, y=66.00, z=260.85], ws['Cow'/257, l='MpServer', x=22.89, y=66.00, z=264.47], aab['Skeleton'/258, l='MpServer', x=19.50, y=21.00, z=282.50], wo['Bat'/259, l='MpServer', x=19.59, y=21.04, z=282.00], zk['Creeper'/260, l='MpServer', x=28.30, y=31.00, z=279.70], zk['Creeper'/261, l='MpServer', x=26.37, y=30.00, z=278.70], zk['Creeper'/262, l='MpServer', x=16.50, y=25.00, z=289.50], zk['Creeper'/263, l='MpServer', x=21.39, y=28.00, z=293.84], zk['Creeper'/264, l='MpServer', x=16.50, y=25.00, z=288.50], wo['Bat'/265, l='MpServer', x=8.03, y=23.02, z=300.73], bpl['Jsrgaming123'/335, l='MpServer', x=-49.38, y=71.00, z=270.50], ws['Cow'/83, l='MpServer', x=-127.55, y=75.00, z=291.39], ws['Cow'/92, l='MpServer', x=-112.11, y=73.00, z=236.38], aad['Spider'/93, l='MpServer', x=-121.50, y=74.00, z=255.50], ws['Cow'/94, l='MpServer', x=-119.19, y=75.00, z=258.46], ws['Cow'/99, l='MpServer', x=-105.39, y=67.00, z=203.32], ws['Cow'/100, l='MpServer', x=-99.18, y=66.00, z=203.49], ws['Cow'/101, l='MpServer', x=-115.16, y=68.00, z=203.49], zk['Creeper'/102, l='MpServer', x=-94.83, y=39.00, z=221.42], ws['Cow'/103, l='MpServer', x=-111.58, y=67.00, z=207.01], ws['Cow'/104, l='MpServer', x=-105.83, y=74.00, z=266.57], zk['Creeper'/105, l='MpServer', x=-97.50, y=21.00, z=302.50], ws['Cow'/106, l='MpServer', x=-103.55, y=71.00, z=296.45], ws['Cow'/107, l='MpServer', x=-107.46, y=71.00, z=299.79], ws['Cow'/108, l='MpServer', x=-96.50, y=72.00, z=291.79], aad['Spider'/115, l='MpServer', x=-89.02, y=25.00, z=202.00], ww['Pig'/116, l='MpServer', x=-89.23, y=64.00, z=198.58], ww['Pig'/117, l='MpServer', x=-81.51, y=64.00, z=193.66], ww['Pig'/118, l='MpServer', x=-81.24, y=65.00, z=196.50], zk['Creeper'/119, l='MpServer', x=-95.21, y=66.00, z=205.51], ww['Pig'/120, l='MpServer', x=-72.53, y=71.00, z=242.28], ws['Cow'/121, l='MpServer', x=-79.47, y=70.00, z=307.23], ws['Cow'/122, l='MpServer', x=-84.49, y=69.00, z=315.03], ww['Pig'/127, l='MpServer', x=-70.30, y=65.00, z=197.51], ze['item.tile.sapling.birch'/128, l='MpServer', x=-66.94, y=73.00, z=237.13], ze['item.tile.sapling.oak'/129, l='MpServer', x=-77.28, y=69.00, z=246.49], ws['Cow'/130, l='MpServer', x=-75.61, y=69.00, z=319.82], ws['Cow'/131, l='MpServer', x=-75.50, y=70.00, z=314.52], wo['Bat'/132, l='MpServer', x=-72.73, y=32.79, z=337.90], ws['Cow'/147, l='MpServer', x=-54.73, y=66.00, z=198.42], ww['Pig'/148, l='MpServer', x=-55.74, y=66.00, z=198.93], aaj['Zombie'/149, l='MpServer', x=-51.50, y=24.00, z=309.50], aab['Skeleton'/150, l='MpServer', x=-53.18, y=14.00, z=330.17], aab['Skeleton'/151, l='MpServer', x=-53.50, y=14.00, z=324.72], aab['Skeleton'/152, l='MpServer', x=-63.50, y=25.00, z=326.50], zk['Creeper'/153, l='MpServer', x=-48.50, y=41.00, z=343.50], wo['Bat'/154, l='MpServer', x=-70.25, y=33.82, z=342.39], aab['Skeleton'/155, l='MpServer', x=-50.56, y=35.00, z=343.28], wo['Bat'/166, l='MpServer', x=-47.77, y=30.03, z=213.75], zk['Creeper'/167, l='MpServer', x=-34.50, y=65.00, z=214.50], aaj['Zombie'/168, l='MpServer', x=-36.43, y=65.00, z=214.80], aaj['Zombie'/169, l='MpServer', x=-42.19, y=69.00, z=224.49], aab['Skeleton'/170, l='MpServer', x=-44.50, y=27.00, z=256.20], aab['Skeleton'/171, l='MpServer', x=-38.30, y=25.00, z=260.50], aab['Skeleton'/172, l='MpServer', x=-41.01, y=27.00, z=259.44], zk['Creeper'/173, l='MpServer', x=-45.50, y=48.00, z=296.17], aab['Skeleton'/174, l='MpServer', x=-47.24, y=24.00, z=318.54], aaj['Zombie'/175, l='MpServer', x=-39.66, y=20.00, z=324.57], ws['Cow'/178, l='MpServer', x=-22.41, y=71.00, z=244.79], wo['Bat'/179, l='MpServer', x=-24.28, y=27.36, z=296.13], aaj['Zombie'/180, l='MpServer', x=-28.40, y=25.00, z=302.97], aah['Witch'/181, l='MpServer', x=-24.50, y=42.00, z=298.50], wo['Bat'/182, l='MpServer', x=-23.19, y=28.54, z=289.42], wo['Bat'/183, l='MpServer', x=-20.44, y=40.10, z=310.56], wo['Bat'/184, l='MpServer', x=-22.67, y=30.85, z=310.53], zk['Creeper'/185, l='MpServer', x=-30.50, y=21.00, z=331.50], aab['Skeleton'/186, l='MpServer', x=-30.50, y=21.00, z=332.50], aab['Skeleton'/187, l='MpServer', x=-31.75, y=17.64, z=341.94], zk['Creeper'/188, l='MpServer', x=-30.50, y=32.00, z=322.50], zk['Creeper'/189, l='MpServer', x=-19.21, y=32.00, z=326.45], zk['Creeper'/190, l='MpServer', x=-28.50, y=54.00, z=323.50], aaj['Zombie'/191, l='MpServer', x=-23.98, y=55.00, z=321.22], aaj['Zombie'/192, l='MpServer', x=-23.30, y=55.00, z=321.70], wo['Bat'/195, l='MpServer', x=-13.23, y=26.52, z=197.91], ws['Cow'/196, l='MpServer', x=-1.50, y=66.00, z=206.50], ws['Cow'/197, l='MpServer', x=-0.69, y=70.00, z=247.85], aaj['Zombie'/198, l='MpServer', x=-1.50, y=57.00, z=269.50], ws['Cow'/199, l='MpServer', x=-6.80, y=67.00, z=268.68], wo['Bat'/200, l='MpServer', x=-18.75, y=21.03, z=278.45], zk['Creeper'/201, l='MpServer', x=-10.50, y=46.00, z=287.50], ws['Cow'/202, l='MpServer', x=-8.74, y=67.00, z=272.82], ws['Cow'/203, l='MpServer', x=-6.53, y=64.00, z=281.16], wo['Bat'/204, l='MpServer', x=-15.80, y=23.05, z=285.48], aaj['Zombie'/205, l='MpServer', x=-10.50, y=29.00, z=331.76], aaj['Zombie'/206, l='MpServer', x=-13.65, y=42.00, z=333.35], aaj['Zombie'/220, l='MpServer', x=9.82, y=24.00, z=197.48], ws['Cow'/221, l='MpServer', x=0.50, y=66.00, z=201.50], ws['Cow'/222, l='MpServer', x=0.50, y=66.00, z=204.50], zk['Creeper'/223, l='MpServer', x=3.50, y=67.00, z=211.50], ws['Cow'/224, l='MpServer', x=1.16, y=67.00, z=211.30], ww['Pig'/225, l='MpServer', x=15.73, y=69.00, z=228.38], ww['Pig'/226, l='MpServer', x=15.54, y=69.00, z=235.22], zk['Creeper'/227, l='MpServer', x=11.50, y=45.00, z=249.50], wo['Bat'/228, l='MpServer', x=6.29, y=20.04, z=267.28], ws['Cow'/229, l='MpServer', x=14.50, y=62.00, z=260.50], ws['Cow'/230, l='MpServer', x=6.80, y=65.00, z=260.49], wo['Bat'/231, l='MpServer', x=15.25, y=19.10, z=292.25], wo['Bat'/232, l='MpServer', x=13.60, y=21.23, z=302.22], ws['Cow'/233, l='MpServer', x=-0.06, y=67.00, z=349.77], ws['Cow'/235, l='MpServer', x=2.22, y=67.00, z=351.50], zk['Creeper'/236, l='MpServer', x=-0.52, y=66.00, z=345.80], wo['Bat'/243, l='MpServer', x=17.77, y=27.10, z=214.25], ww['Pig'/246, l='MpServer', x=22.83, y=69.00, z=225.83], ww['Pig'/247, l='MpServer', x=24.50, y=69.00, z=225.50], zk['Creeper'/248, l='MpServer', x=29.55, y=23.00, z=256.17], ws['Cow'/249, l='MpServer', x=27.53, y=67.00, z=254.84], aab['Skeleton'/250, l='MpServer', x=20.50, y=38.00, z=256.50], aah['Witch'/252, l='MpServer', x=19.17, y=49.00, z=267.33], aab['Skeleton'/253, l='MpServer', x=24.50, y=49.00, z=263.50], aab['Skeleton'/254, l='MpServer', x=22.26, y=49.00, z=264.54], ws['Cow'/255, l='MpServer', x=19.50, y=67.00, z=259.50]]
Retry entities: 0 total; []
Server brand: vanilla
Server type: Integrated singleplayer server
Stacktrace:
at bnj.a(SourceFile:365)
at bel.b(SourceFile:2536)
at bel.a(SourceFile:404)
at net.minecraft.client.main.Main.main(SourceFile:124)

– System Details –
Details:
Minecraft Version: 16w39a
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 188479504 bytes (179 MB) / 362934272 bytes (346 MB) up to 6429081600 bytes (6131 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 16w39a
LWJGL: 2.9.4
OpenGL: GeForce GTX 780 Ti/PCIe/SSE2 GL version 4.5.0 NVIDIA 369.09, 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: 4x Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz
I hope i was helpfully and also please tell me fix to this glitch or mojang fix this glitch