NullPointerException Error When Starting HuskSync Fabric Plugin

[WERDXZ]

Description

When starting the Minecraft server with the HuskSync Fabric plugin, the server fails to start and throws a NullPointerException error.

Version

Compiled from master branch, minecraft version 1.21.1

Server log

[01:00:14] [main/ERROR]: Failed to start the minecraft server
java.lang.RuntimeException: Could not execute entrypoint stage 'server' due to errors, provided by 'husksync' at 'net.william278.husksync.FabricHuskSync'!
    at net.fabricmc.loader.impl.FabricLoaderImpl.lambda$invokeEntrypoints$2(FabricLoaderImpl.java:403) ~[fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.util.ExceptionUtil.gatherExceptions(ExceptionUtil.java:33) ~[fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:401) ~[fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.game.minecraft.Hooks.startServer(Hooks.java:64) ~[fabric-loader-0.16.5.jar:?]
    at net.minecraft.server.Main.main(Main.java:111) [server-intermediary.jar:?]
    at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:480) [fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74) [fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.launch.knot.KnotServer.main(KnotServer.java:23) [fabric-loader-0.16.5.jar:?]
    at net.fabricmc.loader.impl.launch.server.FabricServerLauncher.main(FabricServerLauncher.java:69) [fabric-loader-0.16.5.jar:?]
Caused by: java.lang.NullPointerException: Cannot invoke "net.minecraft.server.MinecraftServer.method_3827()" because "this.minecraftServer" is null
    at net.william278.husksync.FabricHuskSync.getMinecraftVersion(FabricHuskSync.java:336) ~[HuskSync-Fabric-3.7-2d56484+mc.1.21.1.jar:?]
    at net.william278.husksync.util.CompatibilityChecker.checkCompatibility(CompatibilityChecker.java:53) ~[HuskSync-Fabric-3.7-2d56484+mc.1.21.1.jar:?]
    at net.william278.husksync.FabricHuskSync.onInitializeServer(FabricHuskSync.java:124) ~[HuskSync-Fabric-3.7-2d56484+mc.1.21.1.jar:?]
    at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:399) ~[fabric-loader-0.16.5.jar:?]
    ... 6 more

Protential Solution

After reviewing the source code, it appears the issue may stem from the checkCompatibility method using this.minecraftServer before it is initialized. Below is the relevant code snippet:

fabric/src/main/java/net/william278/husksync/FabricHuskSync.java

// Check compatibility
checkCompatibility();

// Load settings and locales
initialize("plugin config & locale files", (plugin) -> {
    loadSettings();
    loadLocales();
    loadServer();
});

// Register commands
initialize("commands", (plugin) -> getUniform().register(PluginCommand.Type.create(this)));

// Load HuskSync after server startup
ServerLifecycleEvents.SERVER_STARTED.register(server -> {
    this.minecraftServer = server;
    this.onEnable();
});