`panic: lost connection to pod` after forwarding is closed

Hi ! I have the following question/issue: go panics panic: lost connection to pod even after port-forwards were closed.

github.com/anthhub/forwarder v1.1.0

Here is simplified code I use. The main function actually is executed in Go routine (it is some e2e tests running in k8s)

package main

import (
    "context"
    "fmt"
    "time"

    "github.com/anthhub/forwarder"
)

func PortForward(options []*forwarder.Option, config string) (*forwarder.Result, error) {
    ret, err := forwarder.WithForwarders(context.Background(), options, config)
    if err != nil {
        fmt.Printf("Error occurred while configuring port-forwarding with config (%s) and options %v", config, &options)
        ret.Close()
        return nil, err
    }

    ports, err := ret.Ready()
    if err != nil {
        fmt.Printf("Errror occurred while waiting for port-forwarding to be ready with config (%s) and options %v", config, options)
        ret.Close()
        return nil, err
    }
    fmt.Printf("Port-forwarding established with ports: %+v\n", ports)
    fmt.Printf("Make sure to close forwarding via Close()")

    return ret, nil
}

func main() {
    const httpsPort int = 443
    const certRenewalTimeoutSeconds = 120
    localPortForwardPort := 26842
    kubeConfig := "~/.kube/config"
    type test struct {
        Namespace  string
        Source     string
        RemotePort int
    }
    tests := []test{
        {
            Namespace:  "default",
            Source:     "svc/my-service-1",
            RemotePort: 8000,
        },
        {
            Namespace:  "default",
            Source:     "svc/my-service-2",
            RemotePort: 8443,
        },
    }

    for _, test := range tests {
        var portForward *forwarder.Result
        portForwardOptions := []*forwarder.Option{
            {
                LocalPort:  localPortForwardPort,
                RemotePort: test.RemotePort,
                Source:     test.Source,
                Namespace:  test.Namespace,
            },
        }

        portForward, err := PortForward(portForwardOptions, kubeConfig)
        if err != nil {
            fmt.Println(err)
        }
        portForwardOpenedAt := time.Now().Unix()
        fmt.Printf("Portforward opened to %d at %d", localPortForwardPort, portForwardOpenedAt)

        close := func(rst *forwarder.Result, port int, timestamp int64) {
            fmt.Printf("Closing portforward %v on port %d opened at %d", rst, port, timestamp)
            rst.Close()
        }
        defer close(portForward, localPortForwardPort, portForwardOpenedAt)
        // do some tests here, this code returns some value
        localPortForwardPort++
        fmt.Printf("Port incremented. Next port-forwarding will be opened at %d. They all will be closed on return from this func", localPortForwardPort)
    }

}

It all works great, in logs after this particular test is concluded I see

2024/06/19 10:30:42 Closing portforward &{0x1041d7c30 0x1041d7ab0 0x1041d79c0} on port 26843 opened at 1718782197
2024/06/19 10:30:42 Closing portforward &{0x1041d7c30 0x1041d7ab0 0x1041d79c0} on port 26842 opened at 1718782153

However down the road, long after all ports were supposedly closed, in the next tests Go panics with

panic: lost connection to pod
goroutine 3903 [running]:
github.com/anthhub/forwarder.portForwardAPod.func1()
    /vendor/github.com/anthhub/forwarder/forwarder.go:164 +0x2d
created by github.com/anthhub/forwarder.portForwardAPod in goroutine 3902
    /vendor/github.com/anthhub/forwarder/forwarder.go:162 +0x419

In my initial implementation I was calling Close() on each iteration manually (not through defer), but on the second iteration port from the first one was still in use somehow, so I resorted to use separate port in each iteration. Now I tried with defer and ports are closed on return (as they should) , but still this issue persists.

Any thoughts will be appreciated.

anthhub / forwarder

`panic: lost connection to pod` after forwarding is closed #10