error

[13:46:09 INFO]: Booting up Velocity 3.4.0-SNAPSHOT (git-e69213f9-b473)...
[13:46:09 INFO]: Loading localizations...
[13:46:10 INFO]: Connections will use epoll channels, libdeflate (Linux x86_64) compression, OpenSSL 3.x.x (Linux x86_64) ciphers
[13:46:10 WARN]: The proxy is running in offline mode! This is a security risk and you will NOT receive any support!
[13:46:10 WARN]: Player info forwarding is disabled! All players will appear to be connecting from the proxy and will have offline-mode UUIDs.
[13:46:10 INFO]: Loading plugins...
[13:46:10 INFO] [limboapi]: Initializing Simple Virtual World system...
[13:46:11 INFO] [limboapi]: Hooking into PlayerList/UpsertPlayerInfo and StateRegistry...
[13:46:11 INFO]: Loaded plugin limboapi 1.1.27-SNAPSHOT (git-f779f2d) by Elytrium (https://elytrium.net/)
[13:46:11 INFO]: Loaded plugin limbohub 1.0.3 by JNNGL
[13:46:11 INFO]: Loaded 3 plugins
[13:46:11 INFO] [limboapi]: Creating and preparing packets...
[13:46:11 INFO] [limboapi]: Loaded!
[13:46:12 WARN] [limboapi]: Block minecraft:leaves is not supported, and was replaced with air.
[13:46:12 ERROR]: Couldn't pass ProxyInitializeEvent to limbohub 1.0.3
java.lang.NullPointerException: Cannot invoke "java.lang.Short.shortValue()" because the return value of "java.util.Map.get(Object)" is null
at net.elytrium.limboapi.server.world.SimpleBlock.(SimpleBlock.java:153) ~[?:?]
at net.elytrium.limboapi.server.world.SimpleBlock.solid(SimpleBlock.java:324) ~[?:?]
at net.elytrium.limboapi.server.world.SimpleBlock.solid(SimpleBlock.java:314) ~[?:?]
at net.elytrium.limboapi.server.world.SimpleBlock.fromModernID(SimpleBlock.java:254) ~[?:?]
at net.elytrium.limboapi.LimboAPI.createSimpleBlock(LimboAPI.java:353) ~[?:?]
at net.elytrium.limboapi.file.StructureNbtFile.toWorld(StructureNbtFile.java:55) ~[?:?]
at net.elytrium.limbohub.LimboHub.reload(LimboHub.java:203) ~[?:?]
at net.elytrium.limbohub.LimboHub.onProxyInitialization(LimboHub.java:155) ~[?:?]
at net.elytrium.limbohub.Lmbda$3.execute(Unknown Source) ~[?:?]
at com.velocitypowered.proxy.event.UntargetedEventHandler$VoidHandler.lambda$buildHandler$0(UntargetedEventHandler.java:56) ~[velocity-3.4.0-SNAPSHOT-473.jar:3.4.0-SNAPSHOT (git-e69213f9-b473)]
at com.velocitypowered.proxy.event.VelocityEventManager.fire(VelocityEventManager.java:677) ~[velocity-3.4.0-SNAPSHOT-473.jar:3.4.0-SNAPSHOT (git-e69213f9-b473)]
at com.velocitypowered.proxy.event.VelocityEventManager.lambda$fire$5(VelocityEventManager.java:542) ~[velocity-3.4.0-SNAPSHOT-473.jar:3.4.0-SNAPSHOT (git-e69213f9-b473)]
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136) ~[?:?]
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635) ~[?:?]
at java.base/java.lang.Thread.run(Thread.java:840) [?:?]
[13:46:12 INFO]: Listening on /[0:0:0:0:0:0:0:0]:25565
[13:46:12 INFO]: Done (3.07s)!

Start at LimboHub.onProxyInitialization and reload, then trace StructureNbtFile.toWorld through LimboAPI.createSimpleBlock and SimpleBlock.fromModernID to the NullPointerException at SimpleBlock.java:153. Determine why the map lookup returns null and verify that proxy initialization completes without this exception.

Written by the indexing model from the issue text.