Teleporting all entities to the player crashed the game
What I expected to happen was...:
A lot of entities get teleported to me.
What actually happened was...:
A lot of entities got teleported to me and then the game crashed almost immediately
Steps to Reproduce:
1. Run the command "/tp @e @p"
2. The game should now crash
Edit.
After some testing in a void world I just got an almost identical crash when I tried to place a chest minecart.
Fixed in 14w27b. Also this is probably a dupe of some other reported issues but that's what happens if you report it straight from the launcher like I did.