Describe the bug
When requesting an item to craft in an interface which is set to blocking mode, the world will crash.
This does result in a crash loop, however it takes a while after load to crash, so its possible to disable blocking mode on the interface and fix it.
I've checked if it was just my setup crashing, but when i tried a simple chest, it still crashes.

To Reproduce

1. Put pattern in interface
2. Enable blocking mode on interface
3. Request item on pattern
4. Crash

Expected behavior
The Item should request fine and start crafting

Additional context
crash log: https://gist.github.com/DerCommander323/ecb482755f7db0f79819a6929edc3d13

Environment

• Minecraft Version: 1.12.2
• AE2 Version: appliedenergistics2-rv6-stable-7-extended_life-v51e.jar
• Forge Version: 14.23.5.2860
• Singleplayer

should be fixed in v51g (when curseforge approves it ) 👍