My function

func RunCommand(cmdPath string, cmdArgs string) (error) {
    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()

    cmd := exec.CommandContext(ctx, cmdPath, cmdArgs)
    stdout, err := cmd.StdoutPipe()
    if err != nil {
        return err
    }
    defer stdout.Close()
    scanner := bufio.NewScanner(stdout)
    err := cmd.Start()
    if err != nil {
        return err
    }

    var wg sync.WaitGroup
    wg.Add(1)

    go func() {
        defer wg.Done()
        for scanner.Scan() {
            doSomething(scanner.Text())
        }
        if scanner.Err() != nil {
            log.Errf("Error reading stdout, %v", scanner.Err())
        }
    }()

    done := make(chan error, 1)
    go func() {
        done <- cmd.Wait()
    }()
    select {
    case <-ctx.Done():
        return ctx.Err()
    case err := <-done:
        if err != nil {
            return err
        }
    }
    wg.Wait()

    return nil
}

I am only able to reproduce this issue a few times where i get this error: Error reading stdout, read |0: file already closed. My understanding is i am closing stdout prior to checking scanner.Err() but why is that happening. I am using cmd.Wait() in a go routine which should wait for scanner.Err() and then close stdout right?