When trying to start an autocrafting job for an item that has multiple crafting steps, you might run in to an arrow like this:
java.lang.ArrayIndexOutOfBoundsExeption: Index 4 out of bounds for length 4
Through trial and error, I've found the cause of this issue being the "Item Substitutions" option when encoding a pattern.
For example, pistons can have any type of wood to be crafted, so one might allow for item substitutions.
If you then also encode a recipe pattern for sticky pistons, and try to craft those, you will run into the above error if you don't have enough pistons in your ME storage.
Obviously the moderator team can't do much about this except wait for the mod's maintainers to release a fix, and then wait for Direwolf20 to update his 1.16 pack. This post is to warn users and provide a temporary workaround.
Just don't use item substitutions for the time being. Sucks if you already have a lot of patterns though.