Error when shutdown.

[lonlf]

[16:35:56] [Server thread/INFO]: [AxSmithing] Disabling AxSmithing v1.9
[16:35:56] [Server thread/ERROR]: Error occurred while disabling AxSmithing v1.9
java.lang.RuntimeException: NMSHandler has not been initialised! This could be due to incorrect usage, or unsupported NMS version!
at AxSmithing-1.9-all.jar/com.artillexstudios.axsmithing.libs.axapi.nms.NMSHandlers.getNmsHandler(NMSHandlers.java:44) ~[AxSmithing-1.9-all.jar:?]
at AxSmithing-1.9-all.jar/com.artillexstudios.axsmithing.libs.axapi.AxPlugin.onDisable(AxPlugin.java:150) ~[AxSmithing-1.9-all.jar:?]
at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:285) ~[purpur-api-1.21.10-R0.1-SNAPSHOT.jar:?]
at io.papermc.paper.plugin.manager.PaperPluginInstanceManager.disablePlugin(PaperPluginInstanceManager.java:237) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at io.papermc.paper.plugin.manager.PaperPluginInstanceManager.disablePlugins(PaperPluginInstanceManager.java:161) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.disablePlugins(PaperPluginManagerImpl.java:97) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at org.bukkit.plugin.SimplePluginManager.disablePlugins(SimplePluginManager.java:541) ~[purpur-api-1.21.10-R0.1-SNAPSHOT.jar:?]
at org.bukkit.craftbukkit.CraftServer.disablePlugins(CraftServer.java:626) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at net.minecraft.server.MinecraftServer.stopServer(MinecraftServer.java:1032) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at net.minecraft.server.dedicated.DedicatedServer.stopServer(DedicatedServer.java:954) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1409) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:388) ~[purpur-1.21.10.jar:1.21.10-2535-0a2dc04]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]