Crash: Rendering entity in world 'java.lang.ClassCastException: adm cannot be cast to adu'

Put the summary of the bug you're having here

What I expected to happen was...:
.. that the game would not crash.

What actually happened was...:
Describe what happened here

I was harvesting vines. I had just finished shearing one row of vines, and was picking up the ones on the ground while looking up at the next row. Durability on the shears was low (in the red) but not exhausted.

Steps to Reproduce:
Sorry. This is the second time I've had this crash, but most of the time everything works fine. I have a row of solid blocks eight rows above the ground with vines on the side (just out of reach from the ground). When the vines descend far enough, I collect them, usually in rows. Both times when the game crashed, I had just finished shearing the row 5 above the ground, and was going back to get the sixth row. I've attached both crash reports.

Wild guess? While looking almost straight up a new vine spawned in my crosshairs. Maybe.

Description: Rendering entity in world

java.lang.ClassCastException: adm cannot be cast to adu
	at bfc$6.a(SourceFile:108)
	at bfc.a(SourceFile:133)
	at bve.a(SourceFile:217)
	at bve.a(SourceFile:135)
	at bve.a(SourceFile:120)
	at bve.a(SourceFile:153)
	at bvc.a(SourceFile:142)
	at bvc.a(SourceFile:18)
	at buo.a(SourceFile:359)
	at buo.a(SourceFile:346)
	at bqk.a(SourceFile:604)
	at bqc.a(SourceFile:1283)
	at bqc.b(SourceFile:1188)
	at bqc.a(SourceFile:1033)
	at beq.av(SourceFile:990)
	at beq.a(SourceFile:395)
	at net.minecraft.client.main.Main.main(SourceFile:124)