I was in the End, way off of the island. There was no Ender Dragon alive. I had used the fill command to make a 20X20 platform out of the new Barrier blocks. Endermen started spawning like crazy on it, I assume because there was nowhere else for them to spawn.

I built a smaller platform out of barriers, went onto it, went into survival mode, and looked at an enderman.

The game crashed to desktop, without presenting the crash report, so I don't think that the Hopper caught it. I have attached the crash report that was logged at that time. Since all it shows are obfuscated class names, I cannot tell what went wrong.