About using go func(){} and call of nil function

[Autumn-27]

The main code is as follows

func Execute(input interface{}, op options.PluginOption) (interface{}, error) {
	data, ok := input.(*types.AssetHttp)
	if !ok {
		return nil, nil
	}

	parameter := op.Parameter
	var filgerFile string
	thread := 20
	if parameter != "" {
		args, err := utils.Tools.ParseArgs(parameter, "finger", "thread")
		if err != nil {
		} else {
			for key, value := range args {
				if value != "" {
					switch key {
					case "finger":
						filgerFile = value
					case "thread":
						thread, _ = strconv.Atoi(value)
					}
				}
			}
		}
	}
	if filgerFile == "" {
		return nil, nil
	}
	fingerFilePath := filepath.Join(global.DictPath, filgerFile)
	content, err := os.ReadFile(fingerFilePath)
	if err != nil {
		op.Log(fmt.Sprintf("read finger error: %v", err))
		return nil, nil
	}
	var fingers Fingerprints
	err = json.Unmarshal(content, &fingers)
	if err != nil {
		op.Log(fmt.Sprintf("json to fingers error: %v", err))
		return nil, nil
	}
	semaphore := make(chan struct{}, thread)
	var wg sync.WaitGroup
	uniqueCms := sync.Map{}
	for _, finp := range fingers.Fingerprint {
		select {
		case <-op.Ctx.Done():
			break
		default:
			semaphore <- struct{}{}
			wg.Add(1)
			go func(finger Fingerprint) {
				defer func() {
					<-semaphore 
					wg.Done()
				}()
				if finger.Location == "body" {
					if finger.Method == "keyword" {
						if iskeyword(data.ResponseBody, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
					if finger.Method == "faviconhash" {
						if data.FavIconMMH3 == finger.Keyword[0] {
							uniqueCms.Store(finger.Cms, true)
						}
					}
					if finger.Method == "regular" {
						if isregular(data.ResponseBody, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
				}

				if finger.Location == "header" {
					if finger.Method == "keyword" {
						if iskeyword(data.RawHeaders, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
					if finger.Method == "regular" {
						if isregular(data.RawHeaders, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
				}
				if finger.Location == "title" {
					if finger.Method == "keyword" {
						if iskeyword(data.Title, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
					if finger.Method == "regular" {
						if isregular(data.Title, finger.Keyword) {
							uniqueCms.Store(finger.Cms, true)
						}
					}
				}
			}(finp)
		}
	}

	wg.Wait()

	var result []string
	existingMap := make(map[string]bool)
	for _, v := range data.Technologies {
		lowerV := strings.ToLower(v)
		if _, exists := existingMap[lowerV]; !exists {
			result = append(result, v)
			existingMap[lowerV] = true 
		}
	}

	uniqueCms.Range(func(key, value interface{}) bool {
		cms := key.(string)
		lowerCms := strings.ToLower(cms)
		if _, exists := existingMap[lowerCms]; !exists {
			result = append(result, cms)
			existingMap[lowerCms] = true 
		}
		return true
	})

	data.Technologies = result
	return nil, nil
}

Execute is registered to the main program through yaegi, and then the main program calls it. By printing the log, I found that panic: reflect.Value.Call: call of nil function appeared in go func(finger Fingerprint) {. I can rule out the problem of Fingerprint because I will execute this code many times, and sometimes there is no error. I can't debug and confirm where the specific cause is. Is there any way to locate the error caused here?