Functional Storage Version: 1.12.2-1.1.3.jar
Titanium Version: 1.18.2-3.5.9-43.jar
Crashlog If Applicable (Upload to pastebin/gist): https://pastebin.com/wKXy3Pp7

When attaching a Storage Drawer Controller Extension instead of a Storage Drawer Controller to a series of drawers, and then hooking up the extension to something like Pretty Pipes (which calls net.minecraftforge.items.IItemHandler.getSlots()), the result returns as null and crashes the Forge server.

Obviously, expected player behaviour is not to do this, however the two blocks look similar and the issue may not be easy to track down. Ideally this would have a more graceful fail state than causing a server crash.