Fixed mixin class types

src/client/java/wtf/hak/survivalfabric/mixin/client/BackgroundRendererMixin.java

@@ -16,7 +16,7 @@ import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 import static wtf.hak.survivalfabric.config.client.ClientConfigManager.getConfig;
 
 @Mixin(value = BackgroundRenderer.class, priority = 910)
-public abstract class BackgroundRendererMixin {
+public class BackgroundRendererMixin {
 
     @Unique
     private static final Fog EMPTY_FOG = new Fog(-8.0f, 1_000_000.0F, FogShape.CYLINDER, 0, 0, 0, 0);

src/client/java/wtf/hak/survivalfabric/mixin/client/GameRendererMixin.java

@@ -8,7 +8,7 @@ import org.spongepowered.asm.mixin.injection.At;
 import wtf.hak.survivalfabric.features.Zoom;
 
 @Mixin(GameRenderer.class)
-public abstract class GameRendererMixin {
+public class GameRendererMixin {
 
     /**
      * Modify Zoom FOV

src/main/java/wtf/hak/survivalfabric/mixin/ServerPlayNetworkHandlerMixin.java

@@ -8,7 +8,7 @@ import org.spongepowered.asm.mixin.injection.ModifyArg;
 import wtf.hak.survivalfabric.config.ConfigManager;
 
 @Mixin(ServerPlayNetworkHandler.class)
-public abstract class ServerPlayNetworkHandlerMixin {
+public class ServerPlayNetworkHandlerMixin {
 
     /**
      * Modify quit message

src/main/java/wtf/hak/survivalfabric/mixin/ServerPlayerEntityMixin.java

@@ -10,7 +10,7 @@ import wtf.hak.survivalfabric.commands.SpectatorCommand;
 import wtf.hak.survivalfabric.config.ConfigManager;
 
 @Mixin(ServerPlayerEntity.class)
-public abstract class ServerPlayerEntityMixin {
+public class ServerPlayerEntityMixin {
 
     /**
      * Change player list name if enabled