go网络请求封装问题

package iybTestTools

import (
    "fmt"
    "io/ioutil"
    "net/http"
    "strings"
)

func HttpReq(mth, api string, reqBody interface{}) (response string) {
    method :=mth
    url := api
    // body := strings.NewReader(=reqBody)
    client := http.Client{}
    if method == "POST"{
        switch t:= reqBody.(type){
        case string:
            body := strings.NewReader(t)
            req, err:= http.NewRequest(method, url, body)
            if err != nil {
                fmt.Println("请求出错： ", err)
                return
            }
            req.Header.Add("Content-type", "application/json")
            resp, err := client.Do(req)
            if err != nil {
                fmt.Println("接口返回错误：", err)
                return
            }
            defer resp.Body.Close()
            responseBody, err := ioutil.ReadAll(resp.Body)
            if err != nil{
                fmt.Println("返回体解析出错： ", err)
                return
            }
            response = string(responseBody)
            return
        default:
            fmt.Println("类型错误")
        }

    }else if method=="GET"{
        req, err := http.NewRequest(method, url, nil)
        if err!= nil {
            fmt.Println("请求出错： ", err)
            return
        }
        req.Header.Add("Content-type", "application/json")
        resp, err := client.Do(req)
        if err != nil {
            fmt.Println("请求出错： ", err)
            return
        }
        defer resp.Body.Close()
        responseBody, err := ioutil.ReadAll(resp.Body)
        if err != nil{
            fmt.Println("返回体解析出错：", err)
            return
        }
        response = string(responseBody)
        return

    }else {
        fmt.Println("非法请求")
    }
    return
}

你的返回值return没有设置具体变量，代码看上去没啥问题