Minecraft crashes trying to save a chunk

When I try quitting to the title screen, it freezes, then Minecraft crashes and it says this:
[13:07:30] [Server thread/ERROR]: Failed to save chunk
e: Saving entity NBT
at rr.e(SourceFile:1322) ~[1.9.1-pre3.jar:?]
at rr.d(SourceFile:1263) ~[1.9.1-pre3.jar:?]
at ass.a(SourceFile:216) ~[1.9.1-pre3.jar:?]
at ass.a(SourceFile:102) [1.9.1-pre3.jar:?]
at lo.b(SourceFile:147) [1.9.1-pre3.jar:?]
at lo.a(SourceFile:166) [1.9.1-pre3.jar:?]
at lp.a(SourceFile:883) [1.9.1-pre3.jar:?]
at net.minecraft.server.MinecraftServer.a(SourceFile:371) [1.9.1-pre3.jar:?]
at byl.a(SourceFile:213) [1.9.1-pre3.jar:?]
at byl.C(SourceFile:144) [1.9.1-pre3.jar:?]
at net.minecraft.server.MinecraftServer.run(SourceFile:457) [1.9.1-pre3.jar:?]
at java.lang.Thread.run(Thread.java:745) [?:1.8.0_25]
Caused by: java.lang.NullPointerException
at ahg.k(SourceFile:129) ~[1.9.1-pre3.jar:?]
at ahh.a(SourceFile:132) ~[1.9.1-pre3.jar:?]
at ze.b(SourceFile:258) ~[1.9.1-pre3.jar:?]
at rr.e(SourceFile:1304) ~[1.9.1-pre3.jar:?]
... 11 more