Hello, firstly thank you for your positive feedback. I'm sorry you're having this incompatibility, so far I've taken a look into this and found that the Ritter Active Item System ItemCore Compatibility.zip appears to be working alongside that crafting plugin. Try giving that version of my plugin a try and let me know how it goes. That version fixes an incompatibility with yanfly item core which had a similar issue of Cannot read property 'id' of null.
From my bit of testing I found no issues when crafting items using the ItemCore Compatibility version of Active Item System, granted I am not too familiar with this crafting plugin yet.
Let me know how it goes! Good luck and Thank you!
Edit:
As a side note: When I commented out my code which fixed the itemcore incompatibility it did indeed mess up this crafting plugin.