ToStringMapString is unable to cast map[string][]interface{} and error is omitted

[Battery233]

Here is my sample code. I tried to turn SampleReq into a map[string]string. However,map["array"] turns out to be empty. I checked the code and found ToStringE() is unable to handle a slice and the error is omitted in the call stack.

package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"github.com/spf13/cast"
)

type SampleReq struct {
	SampleString string  `json:"string"`
	IntArray     []int32 `json:"array"`
}

func main() {
	req := &SampleReq{
		SampleString: "string",
		IntArray:     append(make([]int32, 0), 123),
	}
	reqStr, _ := json.Marshal(req)
	d := json.NewDecoder(bytes.NewReader(reqStr))
	d.UseNumber()
	var mapResult map[string]interface{}
	_ = d.Decode(&mapResult)
	castResult := cast.ToStringMapString(mapResult)
	fmt.Printf("before cast %+v, after cast:%+v", mapResult, castResult) // map["array"] is lost

	// a temporary fix
	b, _ := json.Marshal(mapResult["array"])
	castResult["array"] = string(b)
}