Sorry, I don't know how to generate a crash report on a mac (either way does not work for me).
I got this message at a local server console when destroying/touching a jukebox, and my stream ended:

java.lang.NullPointerException
	at ef.a(SourceFile:310)
	at mj.a(SourceFile:237)
	at mj.a(SourceFile:157)
	at et.a(SourceFile:36)
	at ef.a(SourceFile:214)
	at cg.h(SourceFile:178)
	at cg.d(SourceFile:15)
	at ci.run(SourceFile:114)

After re-login this error appeared, and my house was gone, chunk from jukebox level and upwards was totally gone:

Item entity 7357 has no item?!
t: Loading entity NBT
	at lq.e(SourceFile:1032)
	at lv.a(SourceFile:122)
	at aam.a(SourceFile:271)
	at aam.a(SourceFile:72)
	at aam.a(SourceFile:60)
	at im.f(SourceFile:125)
	at im.c(SourceFile:76)
	at il.<init>(SourceFile:26)
	at ik.a(SourceFile:172)
	at ik.a(SourceFile:203)
	at gm.a(SourceFile:104)
	at gm.c(SourceFile:147)
	at gm.a(SourceFile:81)
	at it.d(SourceFile:164)
	at it.c(SourceFile:56)
	at hu.a(SourceFile:49)
	at ht.b(SourceFile:29)
	at net.minecraft.server.MinecraftServer.r(SourceFile:762)
	at ho.r(SourceFile:248)
	at net.minecraft.server.MinecraftServer.q(SourceFile:679)
	at net.minecraft.server.MinecraftServer.run(SourceFile:613)
	at fy.run(SourceFile:849)
Caused by: java.lang.NullPointerException
	at mj.b(SourceFile:138)
	at px.a(SourceFile:229)
	at px.a(SourceFile:179)
	at lq.e(SourceFile:1027)
	... 21 more