When attempting to connect to a LAN world with this mod enabled, the client is disconnected with the message:
Internal Exception: java.lang.NullPointerException: Cannot invoke "net.minecraft.class_746.method_5667()" because "net.minecraft.class_310.method_1551().field_1724" is null

The host sees the following in chat:

CLIENT_USER joined the game
CLIENT_USER left the game

Here are console logs from both the host and the client:
logs

Environment information:
Processor AMD Ryzen 7 5700G with Radeon Graphics 4.30 GHz
Installed RAM 16.0 GB (15.8 GB usable)
System type 64-bit operating system, x64-based processor
GPU AMD Rx570

Minecraft 1.19.2
Quilt Loader 0.18.8
Java JDK 17
Mod Version 1.19-3.0.1

The error only occurs when Wildfire's Female Gender Mod is enabled, when disabled with the same modlist the client connects fine.

Mods List:

• 3D Skin Layers
• Accurate Maps
• Appleskin
• Applied Energistics 2
• Aquatic Torches
• Architectury
• BetterF3
• BetterLeads
• Blur
• Blahaj
• Borderless Mining
• Charm
• Charm Fixer
• Charmonium (with console workaround applied)
• ChatCalc
• ChoiceTheorem's Overhauled Villages
• Cinderscapes
• Collective
• Concurrent Chunk Managment Engine
• Continuity
• Crops Love Rain
• Custom LAN
• Debugify
• Do a Barrel Roll
• Dynamic FPS
• EasierVillagerTrading
• EMI
• Entity Culling
• Exordium
• Explorify
• Fabric Language Kotlin
• FallingTree
• FerriteCore
• FirstpersonModel
• Grass Seeds
• Half Doors
• Head Index
• High-Speed Rail
• I Know What Im Doing
• Indium
• Infinity and Mending
• Infinity Fix
• Interactic
• Inventory Sorter
• Iris
• Lambda Better Grass
• LambDynamicLights
• LanternsBelong on Walls
• Light Overlay
• Limits Grapple
• Lithium
• Memory Leak Fix
• Mineral Chance
• Mod Menu
• No Chat Reports
• No More Purple
• No Shield Delay
• No Telemetry
• Nullscape
• Numismatic Overhaul
• Omni-Hopper
• OneBar
• OST Overhaul
• Overpowered Mending
• owo
• Placeable Blaze Rods
• PresenceFootsteps
• Puzzle
• Quilt Loading Screen
• Quilted Fabric API
• Raise Sound Limit Simplified
• Realistic Sleep
• Retraining
• Rotten Flesh to Leather
• Smaller Nether POrtals
• Sodium
• Sound Physics Remastered
• Stack to Nearby Chests
• Status Effect Timer
• Subterrestrial
• Tax Free Levels
• Terrestria
• Travelers Backpack
• Traverse
• Trinkets
• True Darkness
• Underwater Enchanting
• Village Spawn Point
• Void Fog
• When Dungeons Arise
• Wildfires Female Gender Mod
• YetAnotherConfigLib
• Zoomify

Additional Notes:
Quilt Modloader is a fork of Fabric Modloader, and has no relation to this bug that I am aware of.
The mod functions perfectly in singleplayer, it is only when attempting to connect to a multiplayer session that the issue occurs.
No issue arises when connecting with Wildfires Female Gender Mod disabled.

If there is any more information needed, do let me know.

Gotcha, will do. I'll have to disable everything else as a few of the mods are Quilt only.

Can you test this again with fabric itself? If it does continue to happen then it's a third-party mod breaking it entirely.

As in just the modloader and nothing else other than dependencies? Or with a different modloader entirely?

As in just the modloader and nothing else other than dependencies? Or with a different modloader entirely?

I meant that as in swap both QSL and Quilt loader with fabric loader and fabric api.

I created some test profiles to check if the fault is Wildfire, the loader, or another mod. The profiles contained only Wildfire in its proper version, and whatever library mods were needed to launch the game. The error did not occur on fabric, but did occur on quilt. Is this something under your umbrella to fix, or should I bring this to the quilt team?

Issue persists on Quilt 1.20.1 with no other mods except dependencies.

Perhaps a patch solution in the meantime could be a toggle for "client only" mode? If the host disables Wildfire, the client can connect just fine. However, if the host has Wildfire enabled, the client is immediately disconnected.

Can anyone confirm if this still happens in the latest version of the mod? I am no longer supporting 1.19.2.

Can anyone confirm if this still happens in the latest version of the mod? I am no longer supporting 1.19.2.

It still happend in 1.20.2 with Wildfire's Female Gender Mod 1.20.2-3.2.1 (Fabric)

Displayed when the client joins:

Received a registry entry that is unknown to this client.
This is usually caused by a mismatched mod set between the client and server. See the client logs for more details.
The following registry entry namespaces may be related:
wildfire_gender

And here is the client's log:
latest.log

The host's dialog has no hints to join the game, and the log has no new updates.

However, if there are no mods installed on the client (including any mod loaders), players can join the host normally