Do not send packet to player not logged in

arclight-common/src/main/java/io/izzel/arclight/common/mixin/forge/PacketDistributorMixin.java

@@ -0,0 +1,24 @@
+package io.izzel.arclight.common.mixin.forge;
+
+import net.minecraft.entity.player.ServerPlayerEntity;
+import net.minecraft.network.IPacket;
+import net.minecraftforge.fml.network.PacketDistributor;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
+
+import java.util.function.Consumer;
+import java.util.function.Supplier;
+
+@Mixin(PacketDistributor.class)
+public class PacketDistributorMixin {
+
+    @Overwrite
+    private Consumer<IPacket<?>> playerConsumer(Supplier<ServerPlayerEntity> entityPlayerMPSupplier) {
+        return p -> {
+            ServerPlayerEntity entity = entityPlayerMPSupplier.get();
+            if (entity.connection != null && entity.connection.netManager != null) {
+                entity.connection.netManager.sendPacket(p);
+            }
+        };
+    }
+}

arclight-common/src/main/resources/mixins.arclight.forge.json

@@ -9,6 +9,7 @@
     "ForgeEventFactoryMixin",
     "ForgeHooksMixin",
     "ForgeInternalHandlerMixin",
-    "NetworkHooksMixin"
+    "NetworkHooksMixin",
+    "PacketDistributorMixin"
   ]
 }