how to set slice value in env

[leavest]

package main

import (
	"flag"
	"fmt"
	"os"

	"github.com/zeromicro/go-zero/core/conf"
)

type Config struct {
	User []string `json:"user,default=abc,env=USER"`
}

func main() {
	os.Setenv("USER", "abc")
	var c3 Config
	err := conf.FillDefault(&c3)
	fmt.Println(c3, err) // {[]} type mismatch for field "user", expect "slice", actual "number"
}

if not set env, it works fine
when set env it return err
how to set slice value in env

[leavest]

I think more examples should be added to the config documentation