The item it errors there is in your craftbag and maybe a new crafting material which is not supported by the addon yet? A new rune or glyph maybe you recently found but wa snot added after the Greymoor patch?
Try this script in the chat box after getting the error message:
Code:
/script d(GetItemLink(5, 166045))
The 1st number in the script is the bagId from the error message. The 2nd number 166045 is the number shown inside the error message at slotIndex! So if this changes replace it in the script as well. This should show you the item's link in the chat so you know which item it is referring to and errors on.