Document kjs errors for empty or invalid items (#4242)

Author: jurrejelle

docs/content/Modpacks/Changes/v7.3.0.md

@@ -12,3 +12,7 @@ HCl. These have been unified to both use Circuit 1. This will (very mildly) brea
 
 - `first` ChanceLogic has been Deprecated as its behavior is highly unreliable, and it will be fully removed in 8.0.0.
   We recommend using `xor` instead.
+
+## KJS Errors
+Previously, empty inputs to KJS recipes (like `.inputItems('minecraft:gravl')`) would silently fail and would not add items.
+We have made inputItems respect recycling logic and as a side effect require valid, non-null inputItems. If an input is null or invalid, it will now throw an error.