KCP Threaded Client Error On Disconnect

[joshuameurey]

Describe the bug
Application produces this error "Skipped Data message handling because connection is null." each time one client is disconnecting normally from the host.

[IMPORTANT] How can we reproduce the issue, step by step:
Please tell us how to reproduce your issue, STEP BY STEP, with one of our built in examples.
-> Configure project to use Threaded KCP transport
-> Build and run a standalone application (this will be the host: client+server)
-> Run application in Unity Editor (this is a pure client), connect to the host
-> Disconnect properly the client (not in any bad/error conditions)
-> Log error appears in Unity Log
It appears that it remains data (bytes) in stack to process when the transport is disconnected

Any bug that can be reproduced, can be fixed.
If we can't reproduce it, we can't fix.

Expected behavior
Since the client is disconnected, no mater what is remaining in bytes data stack, it should not produce error.

Screenshots
N/A

StackTrace
Skipped Data message handling because connection is null. UnityEngine.Debug:LogError (object) Mirror.NetworkClient:OnTransportData (System.ArraySegment1<byte>,int) (at Assets/Mirror/Core/NetworkClient.cs:395) Mirror.ThreadedTransport:ClientEarlyUpdate () (at Assets/Mirror/Transports/Threaded/ThreadedTransport.cs:410) Mirror.NetworkClient:NetworkEarlyUpdate () (at Assets/Mirror/Core/NetworkClient.cs:1489) Mirror.NetworkLoop:NetworkEarlyUpdate () (at Assets/Mirror/Core/NetworkLoop.cs:193)

Desktop (please complete the following information):

• OS: Windows 11
• Build target: Windows
• Unity version: 2022.3.14f1
• Mirror branch: 86.13.4
• KCP version: V1.39 [2023-10-31]

Additional context
Important: this is produced using Threaded KCP transport