Line 217 in the RecipePanel script does not match to anything in my project. Either you changed something in code or I did, but I do not remember changing this script since the very beginning.
Having a look at the code around that line, my suspicion is the item description for each ingredient. My guess is that is what is failing.
C#:
m_IngredientDescriptionPanel.ItemDescriptionUIs[i]
Try to find the description component for the ingredients and make sure it has an array of the same length as the number of ingredients.
See here they both have an array of 4.
Side note: if you change the code make sure to backup your project often and especially before updates. Of course you'll want to copy those scripts and add them in your own folders, you'll also want to change the namespace.
Then you'll also need to replace the components on your menus to point to the correct scripts.
Also a heads up, I haven't got to reworking the crafting UI in v1.1 yet. If there are any functionality you wish for please let me know in advance so that I can take it into account. Quite a lot of the UI will change. Hopefully it'll make a lot more sense and be easier to use.
I'll still need a long time to finish v1.1 though, so you should not worry about it for now.