Stack trace

Caused by: java.lang.NullPointerException: Cannot invoke "org.bukkit.NamespacedKey.getNamespace()" because "key" is null
        at org.bukkit.craftbukkit.util.CraftNamespacedKey.toMinecraft(CraftNamespacedKey.java:22) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
        at io.papermc.paper.util.MCUtil.toResourceKey(MCUtil.java:199) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
        at org.bukkit.craftbukkit.CraftRegistry.get(CraftRegistry.java:199) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
        at org.bukkit.craftbukkit.CraftRegistry.get(CraftRegistry.java:132) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
        at org.bukkit.craftbukkit.util.CraftMagicNumbers.get(CraftMagicNumbers.java:479) ~[paper-1.21.8.jar:1.21.8-60-29c8822]
        at org.bukkit.Sound.valueOf(Sound.java:3498) ~[paper-api-1.21.8-R0.1-SNAPSHOT.jar:?]

Plugin and Datapack List

BetonQuest

Actions to reproduce (if known)

Read from user input a sound, like minecraft:entity.player.levelup99!!!⁩⁩ and use the Sound#valueOf method (from an old api version) with it.

Paper version

This server is running Paper version 1.21.8-60-main@29c8822 (2025-09-06T21:49:13Z) (Implementing API version 1.21.8-R0.1-SNAPSHOT)
You are running the latest version
Previous version: 1.21.4-221-c467df9 (MC: 1.21.4)

Other

I catch the IllegalArgumentException I would expect from the valueOf method. But the NamespacedKey#fromString returns null when it is an invalid key and that is passed to a method where an actual key is expected (see Sound.java).
Checking there for null like at the end of the method would throw the expected Exception instead NPE.
Other OldEnums are "affected" by that too.