Ok, so when I placed and item frame on a iron block it crashed my game and said ---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 5/1/14 2:14 PM
Description: Rendering entity in world

java.lang.NullPointerException: Rendering entity in world
at cce.a(SourceFile:79)
at cce.a(SourceFile:53)
at cce.a(SourceFile:24)
at cbt.a(SourceFile:219)
at cbt.a(SourceFile:199)
at cbt.a(SourceFile:176)
at bxs.a(SourceFile:495)
at bxl.a(SourceFile:1146)
at bxl.b(SourceFile:937)
at bjf.ai(SourceFile:828)
at bjf.f(SourceFile:755)
at net.minecraft.client.main.Main.main(SourceFile:121)

A detailed walkthrough of the error, its code path and all known details is as follows