Got another one for you! Here's the crashlog, and here's a photo of the setup I had before it crashed (granted, no items are in the chest to avoid the crash from happening before I could photograph it:

The coal was pulled out of the left shifter, and seemed to be sending the item to the right shifter, but of course upon arrival, crashed.

EDIT

Also happens if the items get sent out but have no destination at all. Just discovered that. So it wasn't that they were routing towards the other shifter, they simply reached the end of the Pipe line and could not determine where to go, and instead of doing your freezing / locking / jamming animation, they're sending the user to the desktop :P

No, it's just another missing nullcheck.

Fixed, but there's a different bug which happens on world reload attempt. No idea why, maybe it's devenv-only.