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Minecraft and Mod version 🐞
Server and client are both running Fabric 0.100.8 on 1.21, and version 5.3.0 of Easy NPC

Describe the bug 🐞
The client is kicked from the server with the message "Internal Exception: io.netty.handler.codec.EncoderException: Failed to encode packet 'clientbount/minecraft:custom_payload' (easy_npc:open_menu_callback_message)" when shift-right clicking on an npc to configure.

To Reproduce ⚙️
Spawn any npc, then shift-right click

Expected behavior ✔️
The npc configuratoin screen opens.

Screenshots 📸

Debugging 🛠️
Despite enabling debug mode, I was unnable to find a debug.log in the logs folder of either the server or the client.

Is the issue happening in combination with other mods? (If yes, please provide a full list) 🧩
Other mods are:

• Appleskin - 3.0.2+mc1.21
• Architectury API - 13.0.6+fabric
• Armor Statues - v21.0.0-1.21-Fabric
• Arts & Crafts - 1.1.8
• Athena - 4.0.0
• Axiom - 3.2.1
• BadOptimizations - 2.1.4
• Balm - 21.0.14+fabric-1.21
• Beautify: Refabricated - 1.2.1+1.21
• CICADA - 0.8.3+1.21-and-above
• Camerapture - 1.6.0+mc1.21
• Chipped - 4.0.0
• Cloth Config API - 15.0.128+fabric
• Clumps - 18.0.0.1
• Collective - 1.21.0-7.80-fabric+forge+neo
• Comforts - 9.0.0+1.21
• Connectable Chains [Fabric] - 2.4.1+1.21
• Convenient mobGriefing - 2.1.2
• Cooking for Blockheads - 21.0.4+fabric-1.21
• Crate Delight - Farmer's Delight - 2024.07.12-fabric
• CreativeCore - 2.12.4
• Cristel Lib - 1.2.7-fabric
• Discs Where Discs Shouldn't Be - 1.5.5
• Diversity - 1.2.1+1.21
• Double Doors - 1.21.0-5.9-fabric+forge+neo
• Ears (+ Snouts/Muzzles, Tails, Horns, Wings, and More) - 1.4.6
• Elytra Trims - 3.4.3
• Fabric API 0.100.8+1.12
• Fabric Language Kotlin - 1.11.0+kotlin.2.0.0
• FerriteCore - 7.0.0
• Forge Config API Port - v21.0.7-1.12-Fabric
• Friends&Foes (Fabric/Quilt) - fabric-mc1.21-2.0.2
• Handcrafted - 4.0.1
• Highlight - 3.0.0
• Jade - 15.1.5+fabric
• JamLib - 1.0.9+1.21
• Just Mob Heads - 1.21.0-8.3-fabric+forge+neo
• Leaves Be Gone - v21.0.0-1.21-Fabric
• Lithium - mc1.21-0.12.7
• Macaw's Bridges - 3.0.0
• Macaw's Doors - 1.1.1
• Macaw's Fences and Walls - 1.1.2
• Macaw's Lights and Lamps - 1.1.1
• Macaw's Paths and Pavings - 1.0.5
• Macaw's Trapdoors - 1.1.3
• More Bookshelf Variants - 1.0.4+1.21-Fabric
• More Cakes - 1.0.1
• More Chests Variants - 1.5.6+1.21-Fabric
• More Chiseled Bookshelf Variants - 1.5.5
• More Crafting Tables - 1.2.8+1.21-Fabric
• Nature's Compass - 1.21-2.2.6-fabric
• Neruina - Ticking Entity Fixer - 2.1.1-fabric+1.21
• No Chat Reports - Fabric-1.21-v2.8.0
• ObsidianUI - 0.2.7+mc1.21-fabric
• Presence Footsteps - 1.10.0+1.21
• Puzzles Lib - v21.0.18-1.21-Fabric
• Quad - 1.2.7+1.21-Fabric
• Resource Backpack's - 0.7.0-BETA
• Resource Config API - 1.21-2.1.1
• Resource Library - 1.21-2.0.2
• Resourceful Lib - 3.0.9
• RightClickHarvest - 4.3.1+1.21
• Scaffolding Drps Nearby - 1.21.0-3.3-fabric+forge+neo
• ServerCore - 1.5.4+1.21
• Show Me Your Skin! - 1.11.2 +1.21
• Simple Quests - 1.21-1.5.6.b
• Simple Voice Chat - fabric-1.21-2.5.19
• Sit - r28
• Small Ships - 2.0.0-b1.4
• Sodium - mc1.21-0.5.11
• Statue - 4.1+mod
• Text Placeholder API - 2.4.1+1.21
• Tool Trims - 2.2.0
• Towns and Towers - 1.13.2
• UsefulFood Reborn - 1.2.2-1.21-Fabric
• Very Many Players (Fabric) - 0.2.0+beta.7.163+1.21
• Voice Chat Interaction - fabric-1.21-1.0.7
• Wanted - 1.1.1.21-mod
• Waystones - 21.0.8+fabric-1.21
• Where Is It - 2.5.0+1.21
• WorldEdit 7.3.5
• YetAnotherConfigLib - 3.5.0+1.21-fabric

Additional context 📝
There are additional client-side mods, and a few of the listed mods are not installed on client, but the issue did not arise in a singleplayer world, and it continued on the server when playing the exact pack that the server runs, so I do not believe that it is a problem with the other mods.

Duplicate of #267

Thanks for the report, this should be fixed with 5.4.1.