[1.21.1] FDLib/FDBosses causes world to no longer tick, resulting in the world not loading at all.

[StupidRepo]

Removing FDLib + FDBosses immediately fixed the problem. Excerpt from log:

[27Nov2025 17:58:44.594] [ModernFix integrated server watchdog/ERROR] [org.embeddedt.modernfix.world.IntegratedWatchdog/]: A single server tick has taken 40001, more than 40000 milliseconds
[27Nov2025 17:58:45.339] [ModernFix integrated server watchdog/ERROR] [org.embeddedt.modernfix.world.IntegratedWatchdog/]: Thread Dump:
"Render thread" prio=10 Id=1 RUNNABLE
	at TRANSFORMER/fdbosses@2.0.9/com.finderfeed.fdbosses.client.overlay.MalkuthWeaknessOverlay.hasMalkuthSpawnerNearby(MalkuthWeaknessOverlay.java:116)
	at TRANSFORMER/fdbosses@2.0.9/com.finderfeed.fdbosses.client.overlay.MalkuthWeaknessOverlay.tickClient(MalkuthWeaknessOverlay.java:63)
	at java.base@21.0.8/java.lang.invoke.LambdaForm$DMH/0x000001434b02c400.invokeStatic(LambdaForm$DMH)
	at java.base@21.0.8/java.lang.invoke.LambdaForm$MH/0x000001435236a000.invoke(LambdaForm$MH)
	at java.base@21.0.8/java.lang.invoke.LambdaForm$MH/0x000001434b421000.invokeExact_MT(LambdaForm$MH)
	at MC-BOOTSTRAP/net.neoforged.bus/net.neoforged.bus.EventListenerFactory$tickClient/0x000001434c4e8000.invoke(.dynamic)
	at MC-BOOTSTRAP/net.neoforged.bus/net.neoforged.bus.EventBus.post(EventBus.java:360)
	at MC-BOOTSTRAP/net.neoforged.bus/net.neoforged.bus.EventBus.post(EventBus.java:328)
	at TRANSFORMER/neoforge@21.1.213/net.neoforged.neoforge.client.ClientHooks.fireClientTickPre(ClientHooks.java:1070)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.client.Minecraft.tick(Minecraft.java:1787)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.client.Minecraft.runTick(Minecraft.java:1161)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.client.Minecraft.run(Minecraft.java:807)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.client.main.Main.main(Main.java:230)
	at java.base@21.0.8/java.lang.invoke.LambdaForm$DMH/0x000001434b02c400.invokeStatic(LambdaForm$DMH)
	at java.base@21.0.8/java.lang.invoke.LambdaForm$MH/0x000001434b420800.invoke(LambdaForm$MH)
	at java.base@21.0.8/java.lang.invoke.Invokers$Holder.invokeExact_MT(Invokers$Holder)
	at java.base@21.0.8/jdk.internal.reflect.DirectMethodHandleAccessor.invokeImpl(Unknown Source)
	at java.base@21.0.8/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(Unknown Source)
	at java.base@21.0.8/java.lang.reflect.Method.invoke(Unknown Source)
	at MC-BOOTSTRAP/fml_loader@4.0.42/net.neoforged.fml.loading.targets.CommonLaunchHandler.runTarget(CommonLaunchHandler.java:136)
	at MC-BOOTSTRAP/fml_loader@4.0.42/net.neoforged.fml.loading.targets.CommonLaunchHandler.clientService(CommonLaunchHandler.java:124)
	at MC-BOOTSTRAP/fml_loader@4.0.42/net.neoforged.fml.loading.targets.CommonClientLaunchHandler.runService(CommonClientLaunchHandler.java:32)
	at MC-BOOTSTRAP/fml_loader@4.0.42/net.neoforged.fml.loading.targets.CommonLaunchHandler.lambda$launchService$4(CommonLaunchHandler.java:118)
	at MC-BOOTSTRAP/fml_loader@4.0.42/net.neoforged.fml.loading.targets.CommonLaunchHandler$$Lambda/0x000001434b3511f8.run(Unknown Source)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:30)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:53)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.Launcher.run(Launcher.java:103)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.Launcher.main(Launcher.java:74)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26)
	at MC-BOOTSTRAP/cpw.mods.modlauncher@11.0.5/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23)
	at app/cpw.mods.bootstraplauncher@2.0.2/cpw.mods.bootstraplauncher.BootstrapLauncher.run(BootstrapLauncher.java:210)
	at app/cpw.mods.bootstraplauncher@2.0.2/cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:69)

[StupidRepo]

Happened after quitting the world when spawning a Wither. The Wither was still 'spawning' as the world saved and exit. Hopefully this helps :)