Latest version 0.3 will crash servers while 0.2 won't

[13:29:43] [main/ERROR] [ne.mi.fm.ja.FMLModContainer/LOADING]: Caught exception during event RegistryEvent.Registerminecraft:motive dispatch for modid furnish
java.lang.RuntimeException: Attempted to load class net/minecraft/client/Minecraft for invalid dist DEDICATED_SERVER
at net.minecraftforge.fml.loading.RuntimeDistCleaner.processClassWithFlags(RuntimeDistCleaner.java:71) ~[forge-1.16.5-36.2.19.jar:36.2] {}
at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) ~[modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:120) ~[modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:265) ~[modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:136) ~[modlauncher-8.0.9.jar:?] {re:classloading}
at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:98) ~[modlauncher-8.0.9.jar:?] {re:classloading}
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_301] {}
at io.github.wouink.furnish.FurnishManager.registerPaintings(FurnishManager.java:279) ~[furnish:1.16.5-0.3] {re:classloading}
at net.minecraftforge.eventbus.ASMEventHandler_417_FurnishManager_registerPaintings_Register.invoke(.dynamic) ~[?:?] {}
at net.minecraftforge.eventbus.ASMEventHandler.invoke(ASMEventHandler.java:85) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:302) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283) ~[eventbus-4.0.0.jar:?] {}
at net.minecraftforge.fml.javafmlmod.FMLModContainer.acceptEvent(FMLModContainer.java:120) ~[forge:36.2] {re:classloading}
at net.minecraftforge.fml.ModContainer.lambda$buildTransitionHandler$4(ModContainer.java:121) ~[forge:?] {re:classloading}
at java.util.concurrent.CompletableFuture$AsyncRun.run(Unknown Source) ~[?:1.8.0_301] {}
at net.minecraftforge.fml.ModWorkManager$SyncExecutor.driveOne(ModWorkManager.java:56) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.ModWorkManager$DrivenExecutor.drive(ModWorkManager.java:40) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.ModLoader.waitForTransition(ModLoader.java:249) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.ModLoader.dispatchAndHandleError(ModLoader.java:236) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.ModLoader.gatherAndInitializeMods(ModLoader.java:202) ~[forge:?] {re:classloading}
at net.minecraftforge.fml.server.ServerModLoader.load(ServerModLoader.java:44) ~[forge:?] {re:classloading}
at net.minecraft.server.Main.main(Main.java:95) ~[?:?] {re:classloading}
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_301] {}
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_301] {}
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_301] {}
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_301] {}
at net.minecraftforge.fml.loading.FMLServerLaunchProvider.lambda$launchService$0(FMLServerLaunchProvider.java:51) ~[forge-1.16.5-36.2.19.jar:36.2] {}
at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?] {}
at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?] {re:classloading}
at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?] {re:classloading}
at net.minecraftforge.server.ServerMain$Runner.runLauncher(ServerMain.java:63) [forge-1.16.5-36.2.19.jar:?] {}
at net.minecraftforge.server.ServerMain$Runner.access$100(ServerMain.java:60) [forge-1.16.5-36.2.19.jar:?] {}
at net.minecraftforge.server.ServerMain.main(ServerMain.java:57) [forge-1.16.5-36.2.19.jar:?] {}

Hi, thanks for reporting!
I just published 0.3-fix1 on Curse which fixes this bug.
However, I have to drop custom paintings support because paintings don't sync between server and client, sorry about that. This is not directly related to your bug report but I wouldn't have noticed that without it, so thanks!
Have a great day.