Works fine offline, but doesnt load on a hosted server?

[RBLXUSER2008]

[2024-07-01 12:01:36]: Caused by: java.lang.ClassNotFoundException: net.minecraft.class_437[2024-07-01 12:01:36]: at jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?][2024-07-01 12:01:36]: at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226) ~[fabric-loader-0.15.10.jar:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.15.10.jar:?][2024-07-01 12:01:36]: at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?][2024-07-01 12:01:36]: at com.voidreaper.VoidReaper.onInitialize(VoidReaper.java:30) ~[voidreaper-1.20.4-1.0.0.jar:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:384) ~[fabric-loader-0.15.10.jar:?][2024-07-01 12:01:36]: ... 6 more
[2024-07-01 12:01:36]: Caused by: java.lang.ClassNotFoundException: net.minecraft.class_437[2024-07-01 12:01:36]: at jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?][2024-07-01 12:01:36]: at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226) ~[fabric-loader-0.15.10.jar:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119) ~[fabric-loader-0.15.10.jar:?][2024-07-01 12:01:36]: at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?][2024-07-01 12:01:36]: at com.voidreaper.VoidReaper.onInitialize(VoidReaper.java:30) ~[voidreaper-1.20.4-1.0.0.jar:?][2024-07-01 12:01:36]: at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:384) ~[fabric-loader-0.15.10.jar:?]