Blocking a player fails unexpectedly following a login

[Peashooter101]

Problem

Found During: Development Testing
Found By: @RhythmicSys
Developer: @Peashooter101

The player seems to have issues when using /block during a player login. If the player has not fully logged in, there may be an error trying to block this user. This seems to be the more likely scenario but the screenshot below implies the player was fully loaded in?

The console does not report any errors.

The player receives a command response that shows the command failed.

The blocked player is not blocked.

This error does not seem to be easily repeatable.

This error was noticed on branch dev/main/expand_to_mods (PR #8) and has not yet been replicated by released versions.

Upon attempting an unblock, a stacktrace was generated:

/unblock Stacktrace

[21:46:35 ERROR]: Error executing task on Server
java.lang.NullPointerException: Cannot invoke "String.isEmpty()" because "content" is null
    at net.kyori.adventure.text.Component.text(Component.java:849) ~[adventure-api-4.25.0.jar:?]
    at SimplePMs-paper-2.4.2.jar/simplexity.simplepms.paper.commands.Unblock.suggestBlockedUsers(Unblock.java:67) ~[SimplePMs-paper-2.4.2.jar:?]
    at com.mojang.brigadier.tree.ArgumentCommandNode.listSuggestions(ArgumentCommandNode.java:71) ~[brigadier-1.3.10.jar:1.21.10-113-9fc21bc]
    at com.mojang.brigadier.CommandDispatcher.getCompletionSuggestions(CommandDispatcher.java:550) ~[paper-1.21.10.jar:?]
    at com.mojang.brigadier.CommandDispatcher.getCompletionSuggestions(CommandDispatcher.java:530) ~[paper-1.21.10.jar:?]
    at net.minecraft.server.network.ServerGamePacketListenerImpl.sendServerSuggestions(ServerGamePacketListenerImpl.java:911) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.network.ServerGamePacketListenerImpl.lambda$handleCustomCommandSuggestions0$2(ServerGamePacketListenerImpl.java:870) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:176) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1537) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:180) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:150) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1517) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1511) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.recordTaskExecutionTimeWhileWaiting(MinecraftServer.java:1229) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1352) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at net.minecraft.server.MinecraftServer.lambda$spin$2(MinecraftServer.java:384) ~[paper-1.21.10.jar:1.21.10-113-9fc21bc]
    at java.base/java.lang.Thread.run(Thread.java:1583) ~[?:?]