Sometimes when you die, you can't respawn and it stops responding if you click "Title screen." It does not respond again (I waited 15 minutes). When you close the program, it says it crashed with errors like "Null returned as "hitResult", this shouldn't happen!"
It seems to involve dying in or near the nether portal with a lot of items. I noticed a few crashed that were from resizing the window. I did not minimize or click out of the minecraft window.

How I triggered the bug:
1. Hit a pig man and send him through a portal.
2. travel close to the portal in the overworld and wait for him to go back through (he must still be mad at you)
3. Once he goes through, go through the same portal and let him kill you.
4. Click the respawn button. If you do not respawn, click it about 15 times, then click "Title screen." It should stop responding.