Efficiency 4 on netherrack = FastRemove crash

I was making some edits to the nether. I had a efficiency 4, silk touch 1 and unbreaking 3 pickaxe. all of a sudden, my game crashed in the middle of mining. and the crash report (which i have included) said something about fast remove.

The crash report says (server) because it was open to LAN, but noone was actually connected but me.

to reproduce:
1. go to nether or a place with a lot of netherrack
2. mine as much as you can with a efficiency 4+ pick
3. no guarantee but you may get a crash