How to get user list of group

[shirakun]

I have the following code:

package main

import (
	"context"
	"fmt"
	"os"
	"tgtest/util"

	"github.com/gotd/td/telegram"
	"github.com/gotd/td/tg"
)

var accountResult util.AccountResult
var arg = os.Args

func main() {
	accountResult, _ = util.GetAccountInfo(arg[1])
	phone := accountResult.Data.Phone
	// fmt.Println(accountResult.Data.Phone)
	sessionPath := "users/" + phone + ".session"
	// Setting up authentication flow helper based on terminal auth.
	client := telegram.NewClient(accountResult.Data.Settings.AppInfo.ApiId, accountResult.Data.Settings.AppInfo.ApiHash, telegram.Options{
		SessionStorage: &telegram.FileSessionStorage{
			Path: sessionPath,
		},
	})
	ctx := context.Background()
	client.Run(ctx, func(ctx context.Context) error {
		inputChannel := tg.InputChannel{ChannelID: 176*****20, AccessHash: -567**********61977}
		// channelInfo, _ := client.API().ChannelsGetChannels(ctx, []tg.InputChannelClass{&inputChannel})
		// fmt.Println(channelInfo)
		memberInfo, err := client.API().ChannelsGetParticipant(ctx, &tg.ChannelsGetParticipantRequest{Channel: &inputChannel})
		fmt.Println(memberInfo, err)

		return nil
	})
}

But it prompts this error:

root@localhost:/mnt/f/project/golang/tgtest$ go run cmd/test2/main.go 1
ChannelsChannelParticipant(nil) rpcDoRequest: retryUntilAck: send: encode payload: unable to encode invokeWithoutUpdates#bf9459b7: field query: unable to encode channels.getParticipant#a0ab6cc6: field participant is nil

The current account is in this group and the list of group users can be viewed through the official client.
Can anyone give me some advice?