error closing the TcpSocket on iOS

[jok886]

Describe the bug
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To Reproduce
Steps to reproduce the behavior:

1. Go to '.SIP Account'
2. Click on 'Register'
4. See error

Expected behavior
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System Infomation()
Flutter SDK Version:3.6.0
Target OS and Version: Xcode 16.2
Host OS and Version: iPhone11

but android is ok.

2025-03-11 10:00:05.296952+0800 Runner[6141:360862] flutter: [2025-03-11 10:00:05.294] Level.error tcp_socket.dart:128 ::: close() | error closing the TcpSocket: Null check operator used on a null value^[[<…>
2025-03-11 10:00:07.307803+0800 Runner[6141:360862] flutter: [2025-03-11 10:00:07.305] Level.error tcp_socket.dart:128 ::: close() | error closing the TcpSocket: Null check operator used on a null value^[[<…>