NPE when /summon Item

I used the command /summon Item and got the error:

2013-09-05 17:56:40 [SERVER] [SEVERE] Item entity 649623 has no item?!
 u: Loading entity NBT
 	at oc.f(SourceFile:1068)
 	at oi.a(SourceFile:149)
 	at at.b(SourceFile:68)
 	at aa.a(SourceFile:55)
 	at kl.d(SourceFile:496)
 	at kl.a(SourceFile:483)
 	at dw.a(SourceFile:47)
 	at cx.b(SourceFile:64)
 	at kl.e(SourceFile:63)
 	at ko.b(SourceFile:37)
 	at bnj.b(SourceFile:84)
 	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
 	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
 	at bng.s(SourceFile:124)
 	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
 	at hs.run(SourceFile:575)
 Caused by: java.lang.NullPointerException
 	at pd.b(SourceFile:129)
 	at tj.a(SourceFile:233)
 	at tj.a(SourceFile:183)
 	at oc.f(SourceFile:1061)
... 15 more