In a multiplayer server, when I attempt to open the creative menu with Icarus installed, the game crashes with the following error:

Description: Unexpected error

java.lang.NullPointerException: Registry Object not present: icarus:white_feathered_wings
at net.minecraftforge.registries.RegistryObject.get(RegistryObject.java:572) ~[forge-1.20.1-47.3.0-universal.jar%23573!/:?]

None of the Icarus items are present in the Just Enough Items menu in multiplayer either. However they are present and work fine in singleplayer.

Hello o/

What crashes, the server or the client?
and could you send a full log please?