Second instance will continue running even if port is already taken

Describe your environment

• ZeroNet version: 0.7.0

• Operating system: Windows 10

• First instance: C:\Users\filips\AppData\Local\Programs\ZeroNet

• Second instance: D:\Users\filips\Namizje\ZeroNet-win-dist-win64

Describe the problem

Steps to reproduce

1. Create first ZeroNet instance.
2. Confirm that it works.
3. Create a second ZeroNet instance with the same port.
4. It will continue running even if the port is already taken.

Observed results

The second instance will try to start. It will fail because the port for a server is already taken by the first instance.

But for some reason, the process of the second instance won't be killed so it will be still running, but without any usability.

When you will try to open the server of the second instance, it will actually use the first one.

Here is my debug log of the second instance. As you can see, it will detect that port is already taken and stop UiServer. But the process will be still running until I manually kill it from Task Manager.

This issue is mostly based on this Reddit topic.

Expected results

The second instance should detect that port is already taken, inform the user and then stop itself.

在 Windows 10 上启动两个使用同一服务器端口的 ZeroNet 实例来重现问题，然后查看第二个实例对应的链接调试日志。确认系统报告了端口冲突，并且 UiServer 停止，而进程仍保持运行。完成标准是第二个实例通知用户并退出，而不是继续运行。