When i tried to break a dirt block my game crashed

Mod Version: 0.21c
Forge: 10.13.4.1448

Crash File
MultiMC: http://paste.ee/p/wPrsA
Minecraft Crash Log: http://paste.ee/p/iAjjJ

Hurray for more Mojang methods returning null when they shouldn't!

To avoid crashes, enchant the shovel or switch it to destroyer mode (Shift + Right Click) and back.