Unexpected error occurred while generating suggestions for input

Server Implementation

Paper

Server Version

1.20.1

Describe the bug

I have this error:

[09:45:43] [Async Tab Complete Thread - #3/ERROR]: Unexpected error occurred while generating suggestions for input: /mask dark_prismarine,prismarine,sands
java.lang.ClassCastException: class org.enginehub.piston.converter.SuccessfulConversion cannot be cast to class org.enginehub.piston.converter.FailedConversion (org.enginehub.piston.converter.SuccessfulConversion and org.enginehub.piston.converter.FailedConversion are in unnamed module of loader 'FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar' @10854dc5)
	at org.enginehub.piston.impl.CommandParser.conversionFailedException(CommandParser.java:188) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at org.enginehub.piston.impl.CommandParser.parse(CommandParser.java:344) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at org.enginehub.piston.impl.CommandManagerImpl.parse(CommandManagerImpl.java:240) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at org.enginehub.piston.impl.CommandManagerImpl.getSuggestions(CommandManagerImpl.java:190) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.extension.platform.PlatformCommandManager.handleCommandSuggestion(PlatformCommandManager.java:904) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.util.eventbus.MethodHandleEventHandler.dispatch(MethodHandleEventHandler.java:51) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.util.eventbus.EventHandler.handleEvent(EventHandler.java:73) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.util.eventbus.EventBus.dispatch(EventBus.java:193) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.util.eventbus.EventBus.post(EventBus.java:181) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.sk89q.worldedit.bukkit.WorldEditPlugin$AsyncTabCompleteListener.onAsyncTabComplete(WorldEditPlugin.java:690) ~[FastAsyncWorldEdit-Bukkit-2.7.2-SNAPSHOT-557.jar:?]
	at com.destroystokyo.paper.event.executor.MethodHandleEventExecutor.execute(MethodHandleEventExecutor.java:40) ~[paper-api-1.20.1-R0.1-SNAPSHOT.jar:?]
	at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:77) ~[paper-api-1.20.1-R0.1-SNAPSHOT.jar:git-Paper-176]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[paper-api-1.20.1-R0.1-SNAPSHOT.jar:?]
	at io.papermc.paper.plugin.manager.PaperEventManager.callEvent(PaperEventManager.java:54) ~[paper-1.20.1.jar:git-Paper-176]
	at io.papermc.paper.plugin.manager.PaperPluginManagerImpl.callEvent(PaperPluginManagerImpl.java:126) ~[paper-1.20.1.jar:git-Paper-176]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:615) ~[paper-api-1.20.1-R0.1-SNAPSHOT.jar:?]
	at org.bukkit.event.Event.callEvent(Event.java:45) ~[paper-api-1.20.1-R0.1-SNAPSHOT.jar:?]
	at net.minecraft.server.network.ServerGamePacketListenerImpl.lambda$handleCustomCommandSuggestions$8(ServerGamePacketListenerImpl.java:913) ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?]
	at java.lang.Thread.run(Thread.java:1589) ~[?:?]

To Reproduce

1. Use /mask dark_prismarine,prismarine,sands

Expected behaviour

No error

Screenshots / Videos

No response

Error log (if applicable)

No response

Fawe Debugpaste

https://athion.net/ISPaster/paste/view/8dc2485ecc634332a787b48024ad7b20

Fawe Version

FastAsyncWorldEdit-557

Checklist

• I have included a Fawe debugpaste.
• I am using the newest build from https://ci.athion.net/job/FastAsyncWorldEdit/ and the issue still persists.

Anything else?

No response

Start in CommandParser.java, especially conversionFailedException at line 188 and parse at line 344, then follow the getSuggestions entry point in CommandManagerImpl.java. Reproduce the issue with /mask dark_prismarine,prismarine,sands and verify that suggestions no longer produce the reported ClassCastException.