Crashing issue

When I tried to load a singleplayer world it crashes.

[15:12:53] [Server thread/ERROR]: Encountered an unexpected exception
[15:12:53 INFO]: Client> q: Exception getting block type in world
[15:12:53 INFO]: Client> 	at nv.c(SourceFile:147) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at net.minecraft.server.MinecraftServer.v(SourceFile:545) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at net.minecraft.server.MinecraftServer.u(SourceFile:461) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at byn.u(SourceFile:123) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at net.minecraft.server.MinecraftServer.run(SourceFile:377) [14w04a.jar:?]
[15:12:53 INFO]: Client> 	at mc.run(SourceFile:647) [14w04a.jar:?]
[15:12:53 INFO]: Client> Caused by: java.lang.RuntimeException: Already decorating
[15:12:53 INFO]: Client> 	at ail.a(SourceFile:21) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at aif.a(SourceFile:386) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at ain.a(SourceFile:29) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at asc.a(SourceFile:443) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at nl.a(SourceFile:174) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at aqz.a(SourceFile:834) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at nl.c(SourceFile:103) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at nl.d(SourceFile:116) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at ahn.b(SourceFile:273) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at ahn.f(SourceFile:268) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at ahn.c(SourceFile:204) ~[14w04a.jar:?]
[15:12:53 INFO]: Client> 	at ahn.d(SourceFile:219) ~[14w04a.jar:?]