Loading a world with item frames in Minecraft 14w18a will crash the game.
(Tested by loading the same world in 14w17a, and it loaded fine)

Removing the item frame at the location specified in the crash report and loading it up again will still crash the game if other item frames are still there. (it will then specify the next item frame that would be rendered instead).

I'm not familiar enough with the crash reports to figure out exactly what's wrong, but it looks like it has issues rendering the item frames.
The crash report is included as an attachment.