Licowitches will spend their free time performing experiments by throwing Radiant Essence into Conversion Crucibles. This item is tagged to automatically decay in the player's inventory to prevent exploitation. However, it will not decay in any non-player inventory, including chests and hoppers, which leads to several issues.

First, inventory decay for the player is not instant. While it is fast enough to prevent one from using any as they're thrown. One can place a hopper above or below a conversion crucible to stockpile them. At which the player can grab them and place them into a crafting table where they will stop dissappearing and can be used as material like any other.

Second, autonomous crafting systems are able to use the witch-thrown radiant essence without any qualms. This is entirely a mod compatibility issue currently. But still worth keeping in mind if only because of the Crafter block introduced in later versions.

Maybe witch-thrown radiant essence should be another entity instead of minecraft:item?